Anti-TIE2 Antibodies and Uses Thereof

ABSTRACT

The present invention provides antibodies that bind to Tie2 and methods of using same. According to certain embodiments of the invention, the antibodies are fully human antibodies that bind to human Tie2 and block the interaction between Tie2 and one or more Tie2 ligands such as angiopoietin 1 (Ang1), angiopoietin 2 (Ang2), angiopoietin 3 (Ang3) and/or angiopoietin 4 (Ang4). The antibodies of the invention are useful, inter alia, for the treatment of diseases and disorders associated with one or more Tie2 biological activities including angiogenesis. In certain embodiments, pairs of activating Tie-2 antibodies showed an additive effect on the treatment of influenza infection when combined with anti-influenza HA. In other embodiments, prophylactic administration pairs of activating Tie2 antibodies delayed death and improved survival in a lethal model of  E. coli  intoxication (sepsis) over isotype/untreated controls.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 15/445,563, filed Feb. 28, 2017, which is a continuation-in-part of U.S. application Ser. No. 15/373,903, filed on Dec. 9, 2016, now U.S. Pat. No. 10,023,641, which is a continuation of U.S. application Ser. No. 14/671,494, filed on Mar. 27, 2015, now U.S. Pat. No. 9,546,218, which is a divisional of U.S. application Ser. No. 13/586,911, filed on Aug. 16, 2012, now U.S. Pat. No. 9,017,670, which claims the benefit under 35 U.S.C. § 119(e) of provisional application Nos. 61/525,308 filed on Aug. 19, 2011, 61/587,213 filed on Jan. 17, 2012, and 61/674,405, filed Jul. 23, 2012, the disclosures of which are herein incorporated by reference in their entireties.

SEQUENCE LISTING

This application includes an electronic sequence listing in a file named “7100US06-Sequence.txt”, created on Apr. 22, 2019 and containing 111,070 bytes, which is hereby incorporated by reference in its entirety for all purposes.

FIELD OF THE INVENTION

The present invention relates to antibodies, and antigen-binding fragments thereof, which are specific for human Tie2.

BACKGROUND

Angiogenesis is the biological process whereby new blood vessels are formed. Aberrant angiogenesis is associated with several disease conditions including, e.g., proliferative retinopathies, rheumatoid arthritis and psoriasis. In addition, it is well established that angiogenesis is critical for tumor growth and maintenance. Tie2 is a single transmembrane tyrosine kinase receptor that has been localized to the endothelial cells of forming blood vessels and has been shown to play a role in angiogenesis. Tie2 ligands include the angiopoietins (e.g., Ang1, Ang2, Ang3 and Ang4). Blocking the interaction between Tie2 and one or more of its ligands is expected to have beneficial therapeutic effects in settings where it is advantageous to limit or block angiogenesis.

Antibodies to Tie2 are mentioned, e.g., in U.S. Pat. Nos. 6,365,154 and 6,376,653. Nonetheless, there remains a need in the art for novel molecules capable of binding to Tie2, especially anti-Tie2 antibodies that can block the interaction of Tie2 with one or more Tie2 ligands such as Ang2. Such molecules would be useful for various therapeutic and diagnostic purposes.

BRIEF SUMMARY OF THE INVENTION

The present invention provides antibodies that bind human Tie2. The antibodies of the invention are useful, inter alia, for inhibiting Tie2-mediated signaling and for treating diseases and disorders caused by or related to Tie2 activity and/or signaling. According to certain embodiments, the antibodies of the invention block the interaction between Tie2 and one or more Tie2 ligands such as Ang1, Ang2, Ang3, and/or Ang4.

The antibodies of the invention can be full-length (for example, an IgG1 or IgG4 antibody) or may comprise only an antigen-binding portion (for example, a Fab, F(ab′)₂ or scFv fragment), and may be modified to affect functionality, e.g., to eliminate residual effector functions (Reddy et al., 2000, J. Immunol. 164:1925-1933).

The present invention provides anti-Tie2 antibodies that have substantially the same binding characteristics as any of the exemplary anti-Tie2 antibodies described herein. The present invention includes cell lines that produce the anti-Tie2 antibodies described herein. As non-limiting examples, cell lines which produce the exemplary antibodies H1M2055N and H2aM2760N were deposited under terms in accordance with the Budapest Treaty with the American Type Culture Collection (ATCC), 10801 University Blvd., Manassas, Va. 20110-2209 on Dec. 2, 2011. The deposited cell lines have been assigned the following accession numbers: PTA-12295 (H1M2055N) and PTA-12296 (H2aM2760N).

Exemplary anti-Tie2 antibodies of the present invention are listed in Tables 1 and 2 herein. Table 1 sets forth the amino acid sequence identifiers of the heavy chain variable regions (HCVRs), light chain variable regions (LCVRs), heavy chain complementarity determining regions (HCDR1, HCDR2 and HCDR3), and light chain complementarity determining regions (LCDR1, LCDR2 and LCDR3) of the exemplary anti-Tie2 antibodies. Table 2 sets forth the nucleic acid sequence identifiers of the HCVRs, LCVRs, HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3 of the exemplary anti-Tie2 antibodies.

The present invention provides antibodies or antigen-binding fragments thereof that specifically bind Tie2, comprising an HCVR comprising an amino acid sequence selected from any of the HCVR amino acid sequences listed in Table 1, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity thereto.

The present invention also provides antibodies or antigen-binding fragments thereof that specifically bind Tie2, comprising an HCVR and an LCVR amino acid sequence pair (HCVR/LCVR) comprising any of the HCVR amino acid sequences listed in Table 1 paired with any of the LCVR amino acid sequences listed in Table 1. According to certain embodiments, the present invention provides antibodies, or antigen-binding fragments thereof, comprising an HCVR/LCVR amino acid sequence pair contained within any of the exemplary anti-Tie2 antibodies listed in Table 1. In certain embodiments, the HCVR/LCVR amino acid sequence pair is selected from the group consisting of SEQ ID NOs: 20/28, 36/44 and 52/60.

The present invention also provides antibodies or antigen-binding fragments thereof that specifically bind Tie2, comprising a heavy chain CDR1 (HCDR1) comprising an amino acid sequence selected from any of the HCDR1 amino acid sequences listed in Table 1 or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity.

The present invention also provides antibodies or antigen-binding fragments thereof that specifically bind Tie2, comprising a heavy chain CDR2 (HCDR2) comprising an amino acid sequence selected from any of the HCDR2 amino acid sequences listed in Table 1 or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity.

The present invention also provides antibodies or antigen-binding fragments thereof that specifically bind Tie2, comprising a heavy chain CDR3 (HCDR3) comprising an amino acid sequence selected from any of the HCDR3 amino acid sequences listed in Table 1 or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity.

The present invention also provides antibodies or antigen-binding fragments thereof that specifically bind Tie2, comprising a light chain CDR1 (LCDR1) comprising an amino acid sequence selected from any of the LCDR1 amino acid sequences listed in Table 1 or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity.

The present invention also provides antibodies or antigen-binding fragments thereof that specifically bind Tie2, comprising a light chain CDR2 (LCDR2) comprising an amino acid sequence selected from any of the LCDR2 amino acid sequences listed in Table 1 or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity.

The present invention also provides antibodies or antigen-binding fragments thereof that specifically bind Tie2, comprising a light chain CDR3 (LCDR3) comprising an amino acid sequence selected from any of the LCDR3 amino acid sequences listed in Table 1 or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity.

The present invention also provides antibodies or antigen-binding fragments thereof that specifically bind Tie2, comprising an HCDR3 and an LCDR3 amino acid sequence pair (HCDR3/LCDR3) comprising any of the HCDR3 amino acid sequences listed in Table 1 paired with any of the LCDR3 amino acid sequences listed in Table 1. According to certain embodiments, the present invention provides antibodies, or antigen-binding fragments thereof, comprising an HCDR3/LCDR3 amino acid sequence pair contained within any of the exemplary anti-Tie2 antibodies listed in Table 1. In certain embodiments, the HCDR3/LCDR3 amino acid sequence pair is selected from the group consisting of SEQ ID NOs: 24/34, 42/50 and 58/66.

The present invention also provides antibodies or antigen-binding fragments thereof that specifically bind Tie2, comprising a set of six CDRs (i.e., HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3) contained within any of the exemplary anti-Tie2 antibodies listed in Table 1. In certain embodiments, the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 amino acid sequences set is selected from the group consisting of SEQ ID NOs: 22, 24, 26, 30, 32, 34; 38, 40, 42, 46, 48, 50; and 54, 56, 58, 62, 64, 66.

In a related embodiment, the present invention provides antibodies, or antigen-binding fragments thereof that specifically bind Tie2, comprising a set of six CDRs (i.e., HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3) contained within an HCVR/LCVR amino acid sequence pair as defined by any of the exemplary anti-Tie2 antibodies listed in Table 1. For example, the present invention includes antibodies or antigen-binding fragments thereof that specifically bind Tie2, comprising the HCDR1, HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 amino acid sequences set contained within an HCVR/LCVR amino acid sequence pair selected from the group consisting of SEQ ID NOs: 20/28, 36/44 and 52/60. Methods and techniques for identifying CDRs within HCVR and LCVR amino acid sequences are well known in the art and can be used to identify CDRs within the specified HCVR and/or LCVR amino acid sequences disclosed herein. Exemplary conventions that can be used to identify the boundaries of CDRs include, e.g., the Kabat definition, the Chothia definition, and the AbM definition. In general terms, the Kabat definition is based on sequence variability, the Chothia definition is based on the location of the structural loop regions, and the AbM definition is a compromise between the Kabat and Chothia approaches. See, e.g., Kabat, “Sequences of Proteins of Immunological Interest,” National Institutes of Health, Bethesda, Md. (1991); Al-Lazikani et al., J. Mol. Biol. 273:927-948 (1997); and Martin et al., Proc. Natl. Acad. Sci. USA 86:9268-9272 (1989). Public databases are also available for identifying CDR sequences within an antibody.

The present invention also provides nucleic acid molecules encoding anti-Tie2 antibodies or portions thereof. For example, the present invention provides nucleic acid molecules encoding any of the HCVR amino acid sequences listed in Table 1; in certain embodiments the nucleic acid molecule comprises a polynucleotide sequence selected from any of the HCVR nucleic acid sequences listed in Table 2, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity thereto.

The present invention also provides nucleic acid molecules encoding any of the LCVR amino acid sequences listed in Table 1; in certain embodiments the nucleic acid molecule comprises a polynucleotide sequence selected from any of the LCVR nucleic acid sequences listed in Table 2, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity thereto.

The present invention also provides nucleic acid molecules encoding any of the HCDR1 amino acid sequences listed in Table 1; in certain embodiments the nucleic acid molecule comprises a polynucleotide sequence selected from any of the HCDR1 nucleic acid sequences listed in Table 2, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity thereto.

The present invention also provides nucleic acid molecules encoding any of the HCDR2 amino acid sequences listed in Table 1; in certain embodiments the nucleic acid molecule comprises a polynucleotide sequence selected from any of the HCDR2 nucleic acid sequences listed in Table 2, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity thereto.

The present invention also provides nucleic acid molecules encoding any of the HCDR3 amino acid sequences listed in Table 1; in certain embodiments the nucleic acid molecule comprises a polynucleotide sequence selected from any of the HCDR3 nucleic acid sequences listed in Table 2, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity thereto.

The present invention also provides nucleic acid molecules encoding any of the LCDR1 amino acid sequences listed in Table 1; in certain embodiments the nucleic acid molecule comprises a polynucleotide sequence selected from any of the LCDR1 nucleic acid sequences listed in Table 2, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity thereto.

The present invention also provides nucleic acid molecules encoding any of the LCDR2 amino acid sequences listed in Table 1; in certain embodiments the nucleic acid molecule comprises a polynucleotide sequence selected from any of the LCDR2 nucleic acid sequences listed in Table 2, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity thereto.

The present invention also provides nucleic acid molecules encoding any of the LCDR3 amino acid sequences listed in Table 1; in certain embodiments the nucleic acid molecule comprises a polynucleotide sequence selected from any of the LCDR3 nucleic acid sequences listed in Table 2, or a substantially similar sequence thereof having at least 90%, at least 95%, at least 98% or at least 99% sequence identity thereto.

The present invention includes antibodies and antigen-binding fragments thereof comprising the heavy and light chain CDR amino acid sequences (HCDR1, HCDR2, HCDR3, LCDR1, LCDR2 and LCDR3) found within any of the exemplary anti-Tie2 antibodies described herein, including the antibodies produced by the deposited cell lines PTA-12295 and PTA-12296. The present invention also includes antibodies and antigen-binding fragments thereof comprising the heavy and light chain variable domain amino acid sequences (HCVR and LCVR) found within any of the exemplary anti-Tie2 antibodies described herein, including the antibodies produced by the deposited cell lines PTA-12295 and PTA-12296.

The present invention includes any of the exemplary anti-Tie2 antibodies described herein having a modified glycosylation pattern. In some applications, modification to remove undesirable glycosylation sites may be useful, or an antibody lacking a fucose moiety present on the oligosaccharide chain, for example, to increase antibody dependent cellular cytotoxicity (ADCC) function (see Shield et al. (2002) JBC 277:26733). In other applications, modification of galactosylation can be made in order to modify complement dependent cytotoxicity (CDC).

In another aspect, the invention provides pharmaceutical compositions comprising an anti-Tie2 antibody as described herein and a pharmaceutically acceptable carrier. In a related aspect, the invention features compositions which comprise a combination of an anti-Tie2 antibody and a second therapeutic agent. Exemplary agents that may be advantageously combined with an anti-Tie2 antibody include, without limitation, other agents that inhibit anti-Tie2 activity (including other antibodies or antigen-binding fragments thereof, peptide inhibitors, small molecule antagonists, etc.) and/or agents which interfere with Tie2 upstream or downstream signaling.

In yet another aspect, the invention provides methods for inhibiting Tie2 activity using an anti-Tie2 antibody or antigen-binding portion of an antibody of the invention, wherein the therapeutic methods comprise administering a therapeutically effective amount of a pharmaceutical composition comprising an antibody or antigen-binding fragment of an antibody of the invention. The disorder treated is any disease or condition which is improved, ameliorated, inhibited or prevented by removal, inhibition or reduction of Tie2 activity. The anti-Tie2 antibody or antibody fragment of the invention may function to block the interaction between Tie2 and a Tie2 binding partner (e.g., Ang1, Ang2, Ang3, and/or Ang4), or otherwise inhibit the signaling activity of Tie2.

The present invention also includes the use of an anti-Tie2 antibody or antigen binding portion of an antibody of the invention in the manufacture of a medicament for the treatment of a disease or disorder related to or caused by Tie2 activity in a patient.

Other embodiments will become apparent from a review of the ensuing detailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1: Linear depiction of full-length human Tie2 and various deletion constructs used to map the epitope of the anti-Tie2 antibodies of the present invention. Numbers above the constructs indicate the amino acid boundaries of the constructs relative to the full-length Tie2 molecule (SEQ ID NO:1).

FIG. 2: Histogram showing the extent of angiopoietin (hAng1, hAng2, mAng3 or hAng4) binding to a hTie2-coated sensor tip pre-treated with anti-Tie2 antibody H4H2055N or Control I.

FIG. 3: Histogram showing the extent of anti-Tie2 antibody (H4H2055N or Control I) binding to a hTie2-coated sensor tip pre-treated with 100 nM of angiopoietin (hAng1, hAng2, mAng3 or hAng4).

FIGS. 4A and 4B: FIG. 4A shows the H29 tumor growth curves in mice following administration of anti-Tie2 antibody H2M2055N (▪) or Fc control (●). Downward arrow indicates the treatment start date. FIG. 4B shows the tumor growth from the start of treatment in mice treated with anti-Tie2 antibody H2M2055N or Fc control. Asterisk (*) indicates p<0.05 Mann Whitney non-parametric two-tailed t-test.

FIG. 5: H29 tumor vessel density measured at the end of the experiment in mice treated with anti-Tie2 antibody H2M2055N or Fc control. Asterisk (*) indicates p<0.05 Mann Whitney non-parametric two-tailed t-test.

FIGS. 6A and 6B: FIG. 6A shows the Colo305 tumor growth curves in mice following administration of anti-Tie2 antibody H2M2055N (▪) or Fc control (●). Downward arrow indicates the treatment start date. FIG. 6B shows the tumor growth from the start of treatment in mice treated with anti-Tie2 antibody H2M2055N or Fc control. Asterisk (*) indicates p<0.05 Mann Whitney non-parametric two-tailed t-test.

FIG. 7: Colo205 tumor vessel density measured at the end of the experiment in mice treated with anti-Tie2 antibody H2M2055N or Fc control. Asterisk (*) indicates p<0.05 Mann Whitney non-parametric two-tailed t-test.

FIG. 8: Shows the percent permeability of anti-Tie2 antibody pairs H4H2332P/H4H2339P and H4H2340P/H4H2339P in comparison with TNF-α or hIgG4 controls in an in vitro transwell permeability assay.

FIG. 9: Shows therapeutic administration of activating Tie2 mAbs in combination with anti-influenza A hemagglutinin mAb improves survival compared to treatment with the anti-hemagglutinin specific mAb alone after lethal challenge with Influenza A.

FIG. 10: Shows that prophylactic administration of activating Tie2 mAbs, H4H2340P/H4H2339P delays death and improves survival in an E. coli 0111:B4 LPS Sepsis model over isotype/untreated controls.

DETAILED DESCRIPTION

Before the present invention is described, it is to be understood that this invention is not limited to particular methods and experimental conditions described, as such methods and conditions may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. As used herein, the term “about,” when used in reference to a particular recited numerical value, means that the value may vary from the recited value by no more than 1%. For example, as used herein, the expression “about 100” includes 99 and 101 and all values in between (e.g., 99.1, 99.2, 99.3, 99.4, etc.).

Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described. All patents, applications and non-patent publications mentioned in this specification are incorporated herein by reference in their entireties.

Definitions

The expressions “Tie2” and “Tie2 fragment,” as used herein refer to the human Tie2 protein or fragment unless specified as being from a non-human species (e.g., “mouse Tie2,” “mouse Tie2 fragment,” “monkey Tie2,” “monkey Tie2 fragment,” etc.). A “Tie2 fragment” is any portion of Tie2 having fewer amino acids than the full-length Tie2 molecule and which is capable of binding to a Tie2 ligand. Human Tie2 has the amino acid sequence set forth in SEQ ID NO:1. Amino acid sequences of Tie2 molecules from non-human species (e.g., mouse, monkey, rabbit, dog, pig, etc.) are available from public sources such as GenBank (e.g., GenBank accession numbers NP_038718.2 (mouse); NP_001099207.1 (rat); etc).

The term “Tie2 ligand,” as used herein, means a protein with which the Tie2 protein interacts to transmit a biological signal in vivo. The term “Tie2 ligand” includes any of the angiopoietins, including, e.g., Ang1, Ang2, Ang3 and/or Ang4. The term “Ang1,” as used herein, means a protein comprising the amino acid sequence of SEQ ID NO:15, or a portion thereof which is capable of interacting with Tie2. The term “Ang2,” as used herein, means a protein comprising the amino acid sequence of SEQ ID NO:16, or a portion thereof which is capable of interacting with Tie2. The term “Ang3,” as used herein, means a protein comprising the amino acid sequence of SEQ ID NO:17, or a portion thereof which is capable of interacting with Tie2. The term “Ang4,” as used herein, means a protein comprising the amino acid sequence as set forth in of SEQ ID NO:18, or a portion thereof which is capable of interacting with Tie2.

The term “antibody”, as used herein, is intended to refer to immunoglobulin molecules comprising four polypeptide chains, two heavy (H) chains and two light (L) chains inter-connected by disulfide bonds, as well as multimers thereof (e.g., IgM). Each heavy chain comprises a heavy chain variable region (abbreviated herein as HCVR or V_(H)) and a heavy chain constant region. The heavy chain constant region comprises three domains, C_(H)1, C_(H)2 and C_(H)3. Each light chain comprises a light chain variable region (abbreviated herein as LCVR or V_(L)) and a light chain constant region. The light chain constant region comprises one domain (C_(L)1). The V_(H) and V_(L) regions can be further subdivided into regions of hypervariability, termed complementarity determining regions (CDRs), interspersed with regions that are more conserved, termed framework regions (FR). Each V_(H) and V_(L) is composed of three CDRs and four FRs, arranged from amino-terminus to carboxy-terminus in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4. In different embodiments of the invention, the FRs of the anti-Tie2 antibody (or antigen-binding portion thereof) may be identical to the human germline sequences, or may be naturally or artificially modified. An amino acid consensus sequence may be defined based on a side-by-side analysis of two or more CDRs.

The term “antibody,” as used herein, also includes antigen-binding fragments of full antibody molecules. The terms “antigen-binding portion” of an antibody, “antigen-binding fragment” of an antibody, and the like, as used herein, include any naturally occurring, enzymatically obtainable, synthetic, or genetically engineered polypeptide or glycoprotein that specifically binds an antigen to form a complex. Antigen-binding fragments of an antibody may be derived, e.g., from full antibody molecules using any suitable standard techniques such as proteolytic digestion or recombinant genetic engineering techniques involving the manipulation and expression of DNA encoding antibody variable and optionally constant domains. Such DNA is known and/or is readily available from, e.g., commercial sources, DNA libraries (including, e.g., phage-antibody libraries), or can be synthesized. The DNA may be sequenced and manipulated chemically or by using molecular biology techniques, for example, to arrange one or more variable and/or constant domains into a suitable configuration, or to introduce codons, create cysteine residues, modify, add or delete amino acids, etc.

Non-limiting examples of antigen-binding fragments include: (i) Fab fragments; (ii) F(ab′)2 fragments; (iii) Fd fragments; (iv) Fv fragments; (v) single-chain Fv (scFv) molecules; (vi) dAb fragments; and (vii) minimal recognition units consisting of the amino acid residues that mimic the hypervariable region of an antibody (e.g., an isolated complementarity determining region (CDR) such as a CDR3 peptide), or a constrained FR3-CDR3-FR4 peptide. Other engineered molecules, such as domain-specific antibodies, single domain antibodies, domain-deleted antibodies, chimeric antibodies, CDR-grafted antibodies, diabodies, triabodies, tetrabodies, minibodies, nanobodies (e.g. monovalent nanobodies, bivalent nanobodies, etc.), small modular immunopharmaceuticals (SMIPs), and shark variable IgNAR domains, are also encompassed within the expression “antigen-binding fragment,” as used herein.

An antigen-binding fragment of an antibody will typically comprise at least one variable domain. The variable domain may be of any size or amino acid composition and will generally comprise at least one CDR which is adjacent to or in frame with one or more framework sequences. In antigen-binding fragments having a V_(H) domain associated with a V_(L) domain, the V_(H) and V_(L) domains may be situated relative to one another in any suitable arrangement. For example, the variable region may be dimeric and contain V_(H)-V_(H), V_(H)-V_(L) or V_(L)-V_(L) dimers. Alternatively, the antigen-binding fragment of an antibody may contain a monomeric V_(H) or V_(L) domain.

In certain embodiments, an antigen-binding fragment of an antibody may contain at least one variable domain covalently linked to at least one constant domain. Non-limiting, exemplary configurations of variable and constant domains that may be found within an antigen-binding fragment of an antibody of the present invention include: (i) V_(H)-C_(H)1; (ii) V_(H)-C_(H)2; (iii) V_(H)-C_(H)3; (iv) V_(H)-C_(H)1-C_(H)2; (v) V_(H)-C_(H)1-C_(H)2-C_(H)3; (vi) V_(H)-C_(H)2-C_(H)3; (vii) V_(H)-CL; (viii) V_(L)-C_(H)1; (ix) V_(L)-C_(H)2; (x) V_(L)- C_(H)3; (xi) V_(L)-C_(H)1-C_(H)2; (xii) V_(L)-C_(H)1-C_(H)2-C_(H)3; (xiii) V_(L)-C_(H)2-C_(H)3; and (xiv) V_(L)-C_(L). In any configuration of variable and constant domains, including any of the exemplary configurations listed above, the variable and constant domains may be either directly linked to one another or may be linked by a full or partial hinge or linker region. A hinge region may consist of at least 2 (e.g., 5, 10, 15, 20, 40, 60 or more) amino acids which result in a flexible or semi-flexible linkage between adjacent variable and/or constant domains in a single polypeptide molecule. Moreover, an antigen-binding fragment of an antibody of the present invention may comprise a homo-dimer or hetero-dimer (or other multimer) of any of the variable and constant domain configurations listed above in non-covalent association with one another and/or with one or more monomeric V_(H) or V_(L) domain (e.g., by disulfide bond(s)).

As with full antibody molecules, antigen-binding fragments may be monospecific or multispecific (e.g., bispecific). A multispecific antigen-binding fragment of an antibody will typically comprise at least two different variable domains, wherein each variable domain is capable of specifically binding to a separate antigen or to a different epitope on the same antigen. Any multispecific antibody format, including the exemplary bispecific antibody formats disclosed herein, may be adapted for use in the context of an antigen-binding fragment of an antibody of the present invention using routine techniques available in the art.

The antibodies of the present invention may function through complement-dependent cytotoxicity (CDC) or antibody-dependent cell-mediated cytotoxicity (ADCC). “Complement-dependent cytotoxicity” (CDC) refers to lysis of antigen-expressing cells by an antibody of the invention in the presence of complement. “Antibody-dependent cell-mediated cytotoxicity” (ADCC) refers to a cell-mediated reaction in which nonspecific cytotoxic cells that express Fc receptors (FcRs) (e.g., Natural Killer (NK) cells, neutrophils, and macrophages) recognize bound antibody on a target cell and thereby lead to lysis of the target cell. CDC and ADCC can be measured using assays that are well known and available in the art. (See, e.g., U.S. Pat. Nos. 5,500,362 and 5,821,337, and Clynes et al. (1998) Proc. Natl. Acad. Sci. (USA) 95:652-656). The constant region of an antibody is important in the ability of an antibody to fix complement and mediate cell-dependent cytotoxicity. Thus, the isotype of an antibody may be selected on the basis of whether it is desirable for the antibody to mediate cytotoxicity.

The term “human antibody”, as used herein, is intended to include antibodies having variable and constant regions derived from human germline immunoglobulin sequences. The human antibodies of the invention may include amino acid residues not encoded by human germline immunoglobulin sequences (e.g., mutations introduced by random or site-specific mutagenesis in vitro or by somatic mutation in vivo), for example in the CDRs and in particular CDR3. However, the term “human antibody”, as used herein, is not intended to include antibodies in which CDR sequences derived from the germline of another mammalian species, such as a mouse, have been grafted onto human framework sequences.

The term “recombinant human antibody”, as used herein, is intended to include all human antibodies that are prepared, expressed, created or isolated by recombinant means, such as antibodies expressed using a recombinant expression vector transfected into a host cell (described further below), antibodies isolated from a recombinant, combinatorial human antibody library (described further below), antibodies isolated from an animal (e.g., a mouse) that is transgenic for human immunoglobulin genes (see e.g., Taylor et al. (1992) Nucl. Acids Res. 20:6287-6295) or antibodies prepared, expressed, created or isolated by any other means that involves splicing of human immunoglobulin gene sequences to other DNA sequences. Such recombinant human antibodies have variable and constant regions derived from human germline immunoglobulin sequences. In certain embodiments, however, such recombinant human antibodies are subjected to in vitro mutagenesis (or, when an animal transgenic for human Ig sequences is used, in vivo somatic mutagenesis) and thus the amino acid sequences of the V_(H) and V_(L) regions of the recombinant antibodies are sequences that, while derived from and related to human germline V_(H) and V_(L) sequences, may not naturally exist within the human antibody germline repertoire in vivo.

Human antibodies can exist in two forms that are associated with hinge heterogeneity. In one form, an immunoglobulin molecule comprises a stable four chain construct of approximately 150-160 kDa in which the dimers are held together by an interchain heavy chain disulfide bond. In a second form, the dimers are not linked via inter-chain disulfide bonds and a molecule of about 75-80 kDa is formed composed of a covalently coupled light and heavy chain (half-antibody). These forms have been extremely difficult to separate, even after affinity purification.

The frequency of appearance of the second form in various intact IgG isotypes is due to, but not limited to, structural differences associated with the hinge region isotype of the antibody. A single amino acid substitution in the hinge region of the human IgG4 hinge can significantly reduce the appearance of the second form (Angal et al. (1993) Molecular Immunology 30:105) to levels typically observed using a human IgG1 hinge. The instant invention encompasses antibodies having one or more mutations in the hinge, C_(H)2 or C_(H)3 region which may be desirable, for example, in production, to improve the yield of the desired antibody form.

An “isolated antibody,” as used herein, means an antibody that has been identified and separated and/or recovered from at least one component of its natural environment. For example, an antibody that has been separated or removed from at least one component of an organism, or from a tissue or cell in which the antibody naturally exists or is naturally produced, is an “isolated antibody” for purposes of the present invention. An isolated antibody also includes an antibody in situ within a recombinant cell. Isolated antibodies are antibodies that have been subjected to at least one purification or isolation step. According to certain embodiments, an isolated antibody may be substantially free of other cellular material and/or chemicals.

The term “specifically binds,” or the like, means that an antibody or antigen-binding fragment thereof forms a complex with an antigen that is relatively stable under physiologic conditions. Methods for determining whether an antibody specifically binds to an antigen are well known in the art and include, for example, equilibrium dialysis, surface plasmon resonance, and the like. For example, an antibody that “specifically binds” human Tie2, as used in the context of the present invention, includes antibodies that bind human Tie2 or portion thereof with a K_(D) of less than about 1000 nM, less than about 500 nM, less than about 300 nM, less than about 200 nM, less than about 100 nM, less than about 90 nM, less than about 80 nM, less than about 70 nM, less than about 60 nM, less than about 50 nM, less than about 40 nM, less than about 30 nM, less than about 20 nM, less than about 10 nM, less than about 5 nM, less than about 4 nM, less than about 3 nM, less than about 2 nM, less than about 1 nM or less than about 0.5 nM, as measured in a surface plasmon resonance assay. (See, e.g., Example 3, herein). An isolated antibody that specifically binds human Tie2 may, however, have cross-reactivity to other antigens, such as Tie2 molecules from other (non-human) species.

A “neutralizing” or “blocking” antibody, as used herein, is intended to refer to an antibody whose binding to Tie2: (i) interferes with the interaction between Tie2 or a Tie2 fragment and a Tie2 ligand (e.g., an angiopoietin), and/or (ii) results in inhibition of at least one biological function of Tie2. The inhibition caused by a Tie2 neutralizing or blocking antibody need not be complete so long as it is detectable using an appropriate assay. Exemplary assays for detecting TIE2 inhibition are described herein.

The anti-Tie2 antibodies disclosed herein may comprise one or more amino acid substitutions, insertions and/or deletions in the framework and/or CDR regions of the heavy and light chain variable domains as compared to the corresponding germline sequences from which the antibodies were derived. Such mutations can be readily ascertained by comparing the amino acid sequences disclosed herein to germline sequences available from, for example, public antibody sequence databases. The present invention includes antibodies, and antigen-binding fragments thereof, which are derived from any of the amino acid sequences disclosed herein, wherein one or more amino acids within one or more framework and/or CDR regions are mutated to the corresponding residue(s) of the germline sequence from which the antibody was derived, or to the corresponding residue(s) of another human germline sequence, or to a conservative amino acid substitution of the corresponding germline residue(s) (such sequence changes are referred to herein collectively as “germline mutations”). A person of ordinary skill in the art, starting with the heavy and light chain variable region sequences disclosed herein, can easily produce numerous antibodies and antigen-binding fragments which comprise one or more individual germline mutations or combinations thereof. In certain embodiments, all of the framework and/or CDR residues within the V_(H) and/or V_(L) domains are mutated back to the residues found in the original germline sequence from which the antibody was derived. In other embodiments, only certain residues are mutated back to the original germline sequence, e.g., only the mutated residues found within the first 8 amino acids of FR1 or within the last 8 amino acids of FR4, or only the mutated residues found within CDR1, CDR2 or CDR3. In other embodiments, one or more of the framework and/or CDR residue(s) are mutated to the corresponding residue(s) of a different germline sequence (i.e., a germline sequence that is different from the germline sequence from which the antibody was originally derived). Furthermore, the antibodies of the present invention may contain any combination of two or more germline mutations within the framework and/or CDR regions, e.g., wherein certain individual residues are mutated to the corresponding residue of a particular germline sequence while certain other residues that differ from the original germline sequence are maintained or are mutated to the corresponding residue of a different germline sequence. Once obtained, antibodies and antigen-binding fragments that contain one or more germline mutations can be easily tested for one or more desired property such as, improved binding specificity, increased binding affinity, improved or enhanced antagonistic or agonistic biological properties (as the case may be), reduced immunogenicity, etc. Antibodies and antigen-binding fragments obtained in this general manner are encompassed within the present invention.

The present invention also includes anti-Tie2 antibodies comprising variants having one or more conservative substitutions as compared with the HCVR, LCVR and/or CDR amino acid sequences found within the exemplary anti-Tie2 antibodies disclosed herein. For example, the present invention includes anti-Tie2 antibodies having HCVR, LCVR, and/or CDR amino acid sequences with, e.g., 10 or fewer, 8 or fewer, 6 or fewer, 4 or fewer, etc. conservative amino acid substitutions relative to any of the HCVR, LCVR, and/or CDR amino acid sequences of the anti-Tie2 antibodies disclosed herein.

The term “surface plasmon resonance”, as used herein, refers to an optical phenomenon that allows for the analysis of real-time interactions by detection of alterations in protein concentrations within a biosensor matrix, for example using the BIAcore™ system (Biacore Life Sciences division of GE Healthcare, Piscataway, N.J.).

The term “K_(D)”, as used herein, is intended to refer to the equilibrium dissociation constant of a particular antibody-antigen interaction.

The term “epitope” refers to an antigenic determinant that interacts with a specific antigen binding site in the variable region of an antibody molecule known as a paratope. A single antigen may have more than one epitope. Thus, different antibodies may bind to different areas on an antigen and may have different biological effects. Epitopes may be either conformational or linear. A conformational epitope is produced by spatially juxtaposed amino acids from different segments of the linear polypeptide chain. A linear epitope is one produced by adjacent amino acid residues in a polypeptide chain. In certain circumstance, an epitope may include moieties of saccharides, phosphoryl groups, or sulfonyl groups on the antigen.

The term “substantial identity” or “substantially identical,” when referring to a nucleic acid or fragment thereof, indicates that, when optimally aligned with appropriate nucleotide insertions or deletions with another nucleic acid (or its complementary strand), there is nucleotide sequence identity in at least about 95%, and more preferably at least about 96%, 97%, 98% or 99% of the nucleotide bases, as measured by any well-known algorithm of sequence identity, such as FASTA, BLAST or Gap, as discussed below. A nucleic acid molecule having substantial identity to a reference nucleic acid molecule may, in certain instances, encode a polypeptide having the same or substantially similar amino acid sequence as the polypeptide encoded by the reference nucleic acid molecule.

As applied to polypeptides, the term “substantial similarity” or “substantially similar” means that two peptide sequences, when optimally aligned, such as by the programs GAP or BESTFIT using default gap weights, share at least 95% sequence identity, even more preferably at least 98% or 99% sequence identity. Preferably, residue positions which are not identical differ by conservative amino acid substitutions. A “conservative amino acid substitution” is one in which an amino acid residue is substituted by another amino acid residue having a side chain (R group) with similar chemical properties (e.g., charge or hydrophobicity). In general, a conservative amino acid substitution will not substantially change the functional properties of a protein. In cases where two or more amino acid sequences differ from each other by conservative substitutions, the percent sequence identity or degree of similarity may be adjusted upwards to correct for the conservative nature of the substitution. Means for making this adjustment are well-known to those of skill in the art. See, e.g., Pearson (1994) Methods Mol. Biol. 24: 307-331, herein incorporated by reference. Examples of groups of amino acids that have side chains with similar chemical properties include (1) aliphatic side chains: glycine, alanine, valine, leucine and isoleucine; (2) aliphatic-hydroxyl side chains: serine and threonine; (3) amide-containing side chains: asparagine and glutamine; (4) aromatic side chains: phenylalanine, tyrosine, and tryptophan; (5) basic side chains: lysine, arginine, and histidine; (6) acidic side chains: aspartate and glutamate, and (7) sulfur-containing side chains are cysteine and methionine. Preferred conservative amino acids substitution groups are: valine-leucine-isoleucine, phenylalanine-tyrosine, lysine-arginine, alanine-valine, glutamate-aspartate, and asparagine-glutamine. Alternatively, a conservative replacement is any change having a positive value in the PAM250 log-likelihood matrix disclosed in Gonnet et al. (1992) Science 256: 1443-1445, herein incorporated by reference. A “moderately conservative” replacement is any change having a nonnegative value in the PAM250 log-likelihood matrix.

Sequence similarity for polypeptides, which is also referred to as sequence identity, is typically measured using sequence analysis software. Protein analysis software matches similar sequences using measures of similarity assigned to various substitutions, deletions and other modifications, including conservative amino acid substitutions. For instance, GCG software contains programs such as Gap and Bestfit which can be used with default parameters to determine sequence homology or sequence identity between closely related polypeptides, such as homologous polypeptides from different species of organisms or between a wild type protein and a mutein thereof. See, e.g., GCG Version 6.1. Polypeptide sequences also can be compared using FASTA using default or recommended parameters, a program in GCG Version 6.1. FASTA (e.g., FASTA2 and FASTA3) provides alignments and percent sequence identity of the regions of the best overlap between the query and search sequences (Pearson (2000) supra). Another preferred algorithm when comparing a sequence of the invention to a database containing a large number of sequences from different organisms is the computer program BLAST, especially BLASTP or TBLASTN, using default parameters. See, e.g., Altschul et al. (1990) J. Mol. Biol. 215:403-410 and Altschul et al. (1997) Nucleic Acids Res. 25:3389-402, each herein incorporated by reference.

Biological Characteristics of the Antibodies

The present invention includes antibodies that block the interaction between Tie2 and a Tie2 ligand. As used herein, the expression “blocks the interaction between Tie2 and a Tie2 ligand” means that, in an assay in which the physical interaction between Tie2 and a Tie2 ligand can be detected and/or quantified, the addition of an antibody of the invention reduces the interaction between Tie2 and the Tie2 ligand (e.g., Ang1, Ang2, Ang3 and/or Ang4) by at least 50%. A non-limiting, exemplary assay that can be used to determine if an antibody blocks the interaction between human Tie2 and a Tie2 ligand is illustrated in Example 5, herein. In one exemplary embodiment of this assay format, antibodies are mixed with Tie2 protein, and then the antibody/Tie2 mixture is applied to a surface coated with a Tie 2 ligand (in this case, Ang2 protein). After washing away unbound molecules, the amount of Tie2 bound to the Ang2-coated surface is measured. By using varying amounts of antibody in this assay format, the amount of antibody required to block 50% of Tie2 binding to Ang2 can be calculated and expressed as an IC₅₀ value. The format of this assay can be reversed such that Tie2 is coated to surface, antibody is added to the Tie2-coated surface, unbound antibody is washed away, and then a Tie2 ligand is added to the antibody-treated Tie2 surface. The present invention includes anti-Tie2 antibodies that exhibit an IC₅₀ of less than about 100 nM when tested in a Tie2/Tie2 ligand binding assay as illustrated in Example 5, or a substantially similar assay. For example, the invention includes anti-Tie2 antibodies that exhibit an IC₅₀ of less than about 100, 90, 80, 70, 60, 50, 40, 30, 20, 19, 18, 17, 16, 15, 14, 12, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, 0.4, 0.3, or 0.2 nM when tested in a Tie2/Tie2 ligand binding assay as illustrated in Example 5, or a substantially similar assay.

Another assay format that can be used to determine whether an antibody blocks the interaction between human Tie2 and a Tie2 ligand is illustrated in Example 6, herein. In this assay format, a cell line is used which is engineered to express human Tie2 on its surface, and which also includes a reporter construct that causes a detectable signal to be expressed when Tie2 interacts with a Tie2 ligand. The engineered cells are treated with anti-Tie2 antibodies and with Tie2 ligand and the reporter signal is measured. By using varying amounts of antibody in this assay format, the amount of antibody required to inhibit 50% of the reporter signal observed in the absence of antibody can be calculated and expressed as an IC₅₀ value. The present invention includes anti-Tie2 antibodies that exhibit an IC₅₀ of less than about 20 nM when tested in a Tie2/Tie2 ligand binding assay as illustrated in Example 6, or a substantially similar assay. For example, the invention includes anti-Tie2 antibodies that exhibit an IC₅₀ of less than about 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, 0.4, 0.3, 0.2 or 0.1 nM when tested in a Tie2/Tie2 ligand binding assay as described in Example 6, or a substantially similar assay.

The invention also includes Tie2 activating antibodies. For example, the exemplary anti-Tie2 antibodies of the invention H4H2340P, H4H2339P, and H4H2332P were shown to activate Tie2 activity in in vitro and in vivo assays. (See Examples 12 and 13, and Table 10 herein).

Epitope Mapping and Related Technologies

The human Tie2 protein contains the following domains: an Ig1 domain, an Ig2 domain, an EGF repeat domain, an Ig3 domain, and a fibronectin repeat (FN) domain (including FN1, FN2 and FN3). These domains are graphically depicted in Figurel. The present invention includes anti-Tie2 antibodies which bind specifically to an epitope within one or more of the following regions: (a) the Ig1-Ig2-EGF domains (SEQ ID NO:7); (b) the Ig2-EGF domains (SEQ ID NO:8); (c) the EGF domain (SEQ ID NO:9); (d) the Ig3-FN domains (SEQ ID NO:10); and/or (e) the FN domains (SEQ ID NO:11). (See Examples 3 and 4).

According to certain embodiments, the present invention provides anti-Tie2 antibodies which interact with one or more amino acids found within the Ig1 and/or Ig2 domains of Tie2. The epitope(s) may consist of one or more contiguous sequences of 3 or more (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or more) amino acids located within the Ig1 and/or Ig2 domains of Tie2. Alternatively, the epitope may consist of a plurality of non-contiguous amino acids (or amino acid sequences) located within the Ig1 and/or Ig2 domains of Tie2. According to certain embodiments of the present invention, anti-Tie2 antibodies are provided which interact with one or more amino acids located within one or more amino acid segments selected from the group consisting of amino acids 96-106 of SEQ ID NO:7, amino acids 139-152 of SEQ ID NO:7; and amino acids 166-175 of SEQ ID NO:7. For example, the present invention includes anti-Tie2 antibodies which interact with at least one amino acid within each of the aforementioned segments (i.e., within each of amino acids 96-106, 139-152, and 166-175 of SEQ ID NO:7). According to certain embodiments of the present invention, antibodies which interact with amino acids 139-152 and/or 166-175 of SEQ ID NO:7 are capable of blocking the interaction between Tie2 and one or more Tie2 ligands, such as, e.g., Ang2 (see Examples 4-6, herein).

Various techniques known to persons of ordinary skill in the art can be used to determine whether an antibody “interacts with one or more amino acids” within a polypeptide or protein. Exemplary techniques include, e.g., routine cross-blocking assay such as that described Antibodies, Harlow and Lane (Cold Spring Harbor Press, Cold Spring Harb., N.Y.), alanine scanning mutational analysis, peptide blots analysis (Reineke, 2004, Methods Mol Biol 248:443-463), and peptide cleavage analysis. In addition, methods such as epitope excision, epitope extraction and chemical modification of antigens can be employed (Tomer, 2000, Protein Science 9:487-496). Another method that can be used to identify the amino acids within a polypeptide with which an antibody interacts is hydrogen/deuterium exchange detected by mass spectrometry. (See, e.g., Example 4 herein). In general terms, the hydrogen/deuterium exchange method involves deuterium-labeling the protein of interest, followed by binding the antibody to the deuterium-labeled protein. Next, the protein/antibody complex is transferred to water to allow hydrogen-deuterium exchange to occur at all residues except for the residues protected by the antibody (which remain deuterium-labeled). After dissociation of the antibody, the target protein is subjected to protease cleavage and mass spectrometry analysis, thereby revealing the deuterium-labeled residues which correspond to the specific amino acids with which the antibody interacts. See, e.g., Ehring (1999) Analytical Biochemistry 267(2):252-259; Engen and Smith (2001) Anal. Chem. 73:256A-265A.

The present invention includes anti-Tie2 antibodies that bind to the same epitope as any of the specific exemplary antibodies described herein (e.g., antibodies H1M2055N, and H2aM2760N, produced from deposited cell lines PTA-12295 and PTA-12296, respectively or antibodies H4H2332P, H4H2339P, and H4H2340P). Likewise, the present invention also includes anti-Tie2 antibodies that compete for binding to Tie2 or a Tie2 fragment with any of the specific exemplary antibodies described herein (e.g., antibodies H1M2055N, and H2aM2760N, produced from deposited cell lines PTA-12295 and PTA-12296, respectively, or antibodies H4H2332P, H4H2339P, and H4H2340P).

One can easily determine whether an antibody binds to the same epitope as, or competes for binding with, a reference anti-Tie2 antibody by using routine methods known in the art. For example, to determine if a test antibody binds to the same epitope as a reference anti-Tie2 antibody of the invention, the reference antibody is allowed to bind to a Tie2 protein or peptide under saturating conditions. Next, the ability of a test antibody to bind to the Tie2 molecule is assessed. If the test antibody is able to bind to Tie2 following saturation binding with the reference anti-Tie2 antibody, it can be concluded that the test antibody binds to a different epitope than the reference anti-Tie2 antibody. On the other hand, if the test antibody is not able to bind to the Tie2 molecule following saturation binding with the reference anti-Tie2 antibody, then the test antibody may bind to the same epitope as the epitope bound by the reference anti-Tie2 antibody of the invention. Additional routine experimentation (e.g., peptide mutation and binding analyses) can then be carried out to confirm whether the observed lack of binding of the test antibody is in fact due to binding to the same epitope as the reference antibody or if steric blocking (or another phenomenon) is responsible for the lack of observed binding. Experiments of this sort can be performed using ELISA, RIA, Biacore, flow cytometry or any other quantitative or qualitative antibody-binding assay available in the art. In accordance with certain embodiments of the present invention, two antibodies bind to the same (or overlapping) epitope if, e.g., a 1-, 5-, 10-, 20- or 100-fold excess of one antibody inhibits binding of the other by at least 50% but preferably 75%, 90% or even 99% as measured in a competitive binding assay (see, e.g., Junghans et al., Cancer Res. 1990:50:1495-1502). Alternatively, two antibodies are deemed to bind to the same epitope if essentially all amino acid mutations in the antigen that reduce or eliminate binding of one antibody reduce or eliminate binding of the other. Two antibodies are deemed to have “overlapping epitopes” if only a subset of the amino acid mutations that reduce or eliminate binding of one antibody reduce or eliminate binding of the other.

To determine if an antibody competes for binding with a reference anti-Tie2 antibody, the above-described binding methodology is performed in two orientations: In a first orientation, the reference antibody is allowed to bind to a Tie2 molecule under saturating conditions followed by assessment of binding of the test antibody to the Tie2 molecule. In a second orientation, the test antibody is allowed to bind to a Tie2 molecule under saturating conditions followed by assessment of binding of the reference antibody to the Tie2 molecule. If, in both orientations, only the first (saturating) antibody is capable of binding to the Tie2 molecule, then it is concluded that the test antibody and the reference antibody compete for binding to Tie2. As will be appreciated by a person of ordinary skill in the art, an antibody that competes for binding with a reference antibody may not necessarily bind to the same epitope as the reference antibody, but may sterically block binding of the reference antibody by binding an overlapping or adjacent epitope.

Preparation of Human Antibodies

Methods for generating monoclonal antibodies, including fully human monoclonal antibodies are known in the art. Any such known methods can be used in the context of the present invention to make human antibodies that specifically bind to human Tie2.

Using VELOCIMMUNE™ technology or any other known method for generating monoclonal antibodies, high affinity chimeric antibodies to Tie2 are initially isolated having a human variable region and a mouse constant region. As in the experimental section below, the antibodies are characterized and selected for desirable characteristics, including affinity, selectivity, epitope, etc. The mouse constant regions are replaced with a desired human constant region to generate the fully human antibody of the invention, for example wild-type or modified IgG1 or IgG4. While the constant region selected may vary according to specific use, high affinity antigen-binding and target specificity characteristics reside in the variable region.

Bioequivalents

The anti-Tie2 antibodies and antibody fragments of the present invention encompass proteins having amino acid sequences that vary from those of the described antibodies but that retain the ability to bind human Tie2. Such variant antibodies and antibody fragments comprise one or more additions, deletions, or substitutions of amino acids when compared to parent sequence, but exhibit biological activity that is essentially equivalent to that of the described antibodies. Likewise, the anti-Tie2 antibody-encoding DNA sequences of the present invention encompass sequences that comprise one or more additions, deletions, or substitutions of nucleotides when compared to the disclosed sequence, but that encode an anti-Tie2 antibody or antibody fragment that is essentially bioequivalent to an anti-Tie2 antibody or antibody fragment of the invention.

Two antigen-binding proteins, or antibodies, are considered bioequivalent if, for example, they are pharmaceutical equivalents or pharmaceutical alternatives whose rate and extent of absorption do not show a significant difference when administered at the same molar dose under similar experimental conditions, either single does or multiple dose. Some antibodies will be considered equivalents or pharmaceutical alternatives if they are equivalent in the extent of their absorption but not in their rate of absorption and yet may be considered bioequivalent because such differences in the rate of absorption are intentional and are reflected in the labeling, are not essential to the attainment of effective body drug concentrations on, e.g., chronic use, and are considered medically insignificant for the particular drug product studied.

In one embodiment, two antigen-binding proteins are bioequivalent if there are no clinically meaningful differences in their safety, purity, and potency.

In one embodiment, two antigen-binding proteins are bioequivalent if a patient can be switched one or more times between the reference product and the biological product without an expected increase in the risk of adverse effects, including a clinically significant change in immunogenicity, or diminished effectiveness, as compared to continued therapy without such switching.

In one embodiment, two antigen-binding proteins are bioequivalent if they both act by a common mechanism or mechanisms of action for the condition or conditions of use, to the extent that such mechanisms are known.

Bioequivalence may be demonstrated by in vivo and in vitro methods. Bioequivalence measures include, e.g., (a) an in vivo test in humans or other mammals, in which the concentration of the antibody or its metabolites is measured in blood, plasma, serum, or other biological fluid as a function of time; (b) an in vitro test that has been correlated with and is reasonably predictive of human in vivo bioavailability data; (c) an in vivo test in humans or other mammals in which the appropriate acute pharmacological effect of the antibody (or its target) is measured as a function of time; and (d) in a well-controlled clinical trial that establishes safety, efficacy, or bioavailability or bioequivalence of an antibody.

Bioequivalent variants of anti-Tie2 antibodies of the invention may be constructed by, for example, making various substitutions of residues or sequences or deleting terminal or internal residues or sequences not needed for biological activity. For example, cysteine residues not essential for biological activity can be deleted or replaced with other amino acids to prevent formation of unnecessary or incorrect intramolecular disulfide bridges upon renaturation. In other contexts, bioequivalent antibodies may include anti-Tie2 antibody variants comprising amino acid changes which modify the glycosylation characteristics of the antibodies, e.g., mutations which eliminate or remove glycosylation.

Species Selectivity and Species Cross-Reactivity

According to certain embodiments of the invention, the anti-Tie2 antibodies bind to human Tie2 but not to Tie2 from other species. The present invention also includes anti-Tie2 antibodies that bind to human Tie2 and to Tie2 from one or more non-human species. For example, the anti-Tie2 antibodies of the invention may specifically bind to human Tie2 as well as to a rodent Tie2 (e.g., Tie2 from mouse or rat). An exemplary construct that can be used to determine whether an antibody specifically binds mouse Tie2 is the construct having the amino acid sequence of SEQ ID NO:6; an exemplary construct that can be used to determine whether an antibody specifically binds rat Tie2 is the construct having the amino acid sequence of SEQ ID NO:5. The use of these constructs to assess anti-Tie2 antibody binding is illustrated in Example 3, herein.

Immunoconjugates

The invention encompasses anti-Tie2 monoclonal antibodies conjugated to a therapeutic moiety (“immunoconjugate”), such as a cytotoxin, a chemotherapeutic drug, an immunosuppressant or a radioisotope. Cytotoxic agents include any agent that is detrimental to cells. Examples of suitable cytotoxic agents and chemotherapeutic agents for forming immunoconjugates are known in the art, (see for example, WO 05/103081).

Multispecific Antibodies

The antibodies of the present invention may be monospecific, bi-specific, or multispecific. Multispecific antibodies may be specific for different epitopes of one target polypeptide or may contain antigen-binding domains specific for more than one target polypeptide. See, e.g., Tutt et al., 1991, J. Immunol. 147:60-69; Kufer et al., 2004, Trends Biotechnol. 22:238-244. The anti-Tie2 antibodies of the present invention can be linked to or co-expressed with another functional molecule, e.g., another peptide or protein. For example, an antibody or fragment thereof can be functionally linked (e.g., by chemical coupling, genetic fusion, noncovalent association or otherwise) to one or more other molecular entities, such as another antibody or antibody fragment to produce a bi-specific or a multispecific antibody with a second binding specificity. For example, the present invention includes bi-specific antibodies wherein one arm of an immunoglobulin is specific for human Tie2 or a fragment thereof, and the other arm of the immunoglobulin is specific for a second therapeutic target or is conjugated to a therapeutic moiety such as a trypsin inhibitor.

An exemplary bi-specific antibody format that can be used in the context of the present invention involves the use of a first immunoglobulin (Ig) C_(H)3 domain and a second Ig C_(H)3 domain, wherein the first and second Ig C_(H)3 domains differ from one another by at least one amino acid, and wherein at least one amino acid difference reduces binding of the bispecific antibody to Protein A as compared to a bi-specific antibody lacking the amino acid difference. In one embodiment, the first Ig C_(H)3 domain binds Protein A and the second Ig C_(H)3 domain contains a mutation that reduces or abolishes Protein A binding such as an H95R modification (by IMGT exon numbering; H435R by EU numbering). The second C_(H)3 may further comprise a Y96F modification (by IMGT; Y436F by EU). Further modifications that may be found within the second C_(H)3 include: D16E, L18M, N44S, K52N, V57M, and V821 (by IMGT; D356E, L358M, N384S, K392N, V397M, and V4221 by EU) in the case of IgG1 antibodies; N44S, K52N, and V821 (IMGT; N384S, K392N, and V4221 by EU) in the case of IgG2 antibodies; and Q15R, N44S, K52N, V57M, R69K, E79Q, and V821 (by IMGT; Q355R, N384S, K392N, V397M, R409K, E419Q, and V4221 by EU) in the case of IgG4 antibodies. Variations on the bi-specific antibody format described above are contemplated within the scope of the present invention.

Therapeutic Formulation and Administration

The invention provides pharmaceutical compositions comprising the anti-Tie2 antibodies or antigen-binding fragments thereof of the present invention. The pharmaceutical compositions of the invention are formulated with suitable carriers, excipients, and other agents that provide improved transfer, delivery, tolerance, and the like. A multitude of appropriate formulations can be found in the formulary known to all pharmaceutical chemists: Remington's Pharmaceutical Sciences, Mack Publishing Company, Easton, Pa. These formulations include, for example, powders, pastes, ointments, jellies, waxes, oils, lipids, lipid (cationic or anionic) containing vesicles (such as LIPOFECTIN™), DNA conjugates, anhydrous absorption pastes, oil-in-water and water-in-oil emulsions, emulsions carbowax (polyethylene glycols of various molecular weights), semi-solid gels, and semi-solid mixtures containing carbowax. See also Powell et al. “Compendium of excipients for parenteral formulations” PDA (1998) J Pharm Sci Technol 52:238-311.

The dose of antibody administered to a patient may vary depending upon the age and the size of the patient, target disease, conditions, route of administration, and the like. The preferred dose is typically calculated according to body weight or body surface area. When an antibody of the present invention is used for treating a condition or disease associated with Tie2 activity in an adult patient, it may be advantageous to intravenously administer the antibody of the present invention normally at a single dose of about 0.01 to about 20 mg/kg body weight, more preferably about 0.02 to about 7, about 0.03 to about 5, or about 0.05 to about 3 mg/kg body weight. Depending on the severity of the condition, the frequency and the duration of the treatment can be adjusted. Effective dosages and schedules for administering Tie2 antibodies may be determined empirically; for example, patient progress can be monitored by periodic assessment, and the dose adjusted accordingly. Moreover, interspecies scaling of dosages can be performed using well-known methods in the art (e.g., Mordenti et al., 1991, Pharmaceut. Res. 8:1351).

Various delivery systems are known and can be used to administer the pharmaceutical composition of the invention, e.g., encapsulation in liposomes, microparticles, microcapsules, recombinant cells capable of expressing the mutant viruses, receptor mediated endocytosis (see, e.g., Wu et al., 1987, J. Biol. Chem. 262:4429-4432). Methods of introduction include, but are not limited to, intradermal, intramuscular, intraperitoneal, intravenous, subcutaneous, intranasal, epidural, and oral routes. The composition may be administered by any convenient route, for example by infusion or bolus injection, by absorption through epithelial or mucocutaneous linings (e.g., oral mucosa, rectal and intestinal mucosa, etc.) and may be administered together with other biologically active agents. Administration can be systemic or local.

A pharmaceutical composition of the present invention can be delivered subcutaneously or intravenously with a standard needle and syringe. In addition, with respect to subcutaneous delivery, a pen delivery device readily has applications in delivering a pharmaceutical composition of the present invention. Such a pen delivery device can be reusable or disposable. A reusable pen delivery device generally utilizes a replaceable cartridge that contains a pharmaceutical composition. Once all of the pharmaceutical composition within the cartridge has been administered and the cartridge is empty, the empty cartridge can readily be discarded and replaced with a new cartridge that contains the pharmaceutical composition. The pen delivery device can then be reused. In a disposable pen delivery device, there is no replaceable cartridge. Rather, the disposable pen delivery device comes prefilled with the pharmaceutical composition held in a reservoir within the device. Once the reservoir is emptied of the pharmaceutical composition, the entire device is discarded.

Numerous reusable pen and autoinjector delivery devices have applications in the subcutaneous delivery of a pharmaceutical composition of the present invention. Examples include, but are not limited to AUTOPEN™ (Owen Mumford, Inc., Woodstock, UK), DISETRONIC™ pen (Disetronic Medical Systems, Bergdorf, Switzerland), HUMALOG MIX 75/25™ pen, HUMALOG™ pen, HUMALIN 70/30™ pen (Eli Lilly and Co., Indianapolis, Ind.), NOVOPEN™ I, II and III (Novo Nordisk, Copenhagen, Denmark), NOVOPEN JUNIOR™ (Novo Nordisk, Copenhagen, Denmark), BD™ pen (Becton Dickinson, Franklin Lakes, N.J.), OPTIPEN™, OPTIPEN PRO™, OPTIPEN STARLET™, and OPTICLIK™ (sanofi-aventis, Frankfurt, Germany), to name only a few. Examples of disposable pen delivery devices having applications in subcutaneous delivery of a pharmaceutical composition of the present invention include, but are not limited to the SOLOSTAR™ pen (sanofi-aventis), the FLEXPEN™ (Novo Nordisk), and the KWIKPEN™ (Eli Lilly), the SURECLICK™ Autoinjector (Amgen, Thousand Oaks, Calif.), the PENLET™ (Haselmeier, Stuttgart, Germany), the EPIPEN (Dey, L.P.), and the HUMIRA™ Pen (Abbott Labs, Abbott Park Ill.), to name only a few.

In certain situations, the pharmaceutical composition can be delivered in a controlled release system. In one embodiment, a pump may be used (see Langer, supra; Sefton, 1987, CRC Crit. Ref. Biomed. Eng. 14:201). In another embodiment, polymeric materials can be used; see, Medical Applications of Controlled Release, Langer and Wise (eds.), 1974, CRC Pres., Boca Raton, Fla. In yet another embodiment, a controlled release system can be placed in proximity of the composition's target, thus requiring only a fraction of the systemic dose (see, e.g., Goodson, 1984, in Medical Applications of Controlled Release, supra, vol. 2, pp. 115-138). Other controlled release systems are discussed in the review by Langer, 1990, Science 249:1527-1533.

The injectable preparations may include dosage forms for intravenous, subcutaneous, intracutaneous and intramuscular injections, drip infusions, etc. These injectable preparations may be prepared by methods publicly known. For example, the injectable preparations may be prepared, e.g., by dissolving, suspending or emulsifying the antibody or its salt described above in a sterile aqueous medium or an oily medium conventionally used for injections. As the aqueous medium for injections, there are, for example, physiological saline, an isotonic solution containing glucose and other auxiliary agents, etc., which may be used in combination with an appropriate solubilizing agent such as an alcohol (e.g., ethanol), a polyalcohol (e.g., propylene glycol, polyethylene glycol), a nonionic surfactant [e.g., polysorbate 80, HCO-50 (polyoxyethylene (50 mol) adduct of hydrogenated castor oil)], etc. As the oily medium, there are employed, e.g., sesame oil, soybean oil, etc., which may be used in combination with a solubilizing agent such as benzyl benzoate, benzyl alcohol, etc. The injection thus prepared is preferably filled in an appropriate ampoule.

Advantageously, the pharmaceutical compositions for oral or parenteral use described above are prepared into dosage forms in a unit dose suited to fit a dose of the active ingredients. Such dosage forms in a unit dose include, for example, tablets, pills, capsules, injections (ampoules), suppositories, etc. The amount of the aforesaid antibody contained is generally about 5 to about 500 mg per dosage form in a unit dose; especially in the form of injection, it is preferred that the aforesaid antibody is contained in about 5 to about 100 mg and in about 10 to about 250 mg for the other dosage forms. In various embodiments, certain antibodies and antigen-binding fragments of the invention (e.g., antibodies comprising the CDRs or variable regions of H4H2332P, H4H2339P or H4H2340P) can be used to treat or prevent vascular leak, such as for example, vascular leak associated with infections (e.g., influenza or sepsis), stroke, transplants, and eye diseases. In some cases, certain combinations of these antibodies can be used to treat and/or prevent such conditions (e.g., influenza infection and/or sepsis). For example, a combination of H4H2332P and H4H2339P, or a combination of H4H2340P and H4H2339P can be used.

Therapeutic Uses of the Antibodies

The antibodies of the invention are useful, inter alia, for the treatment, prevention and/or amelioration of any disease or disorder associated with Tie2 activity, including diseases or disorders associated with angiogenesis. The antibodies and antigen-binding fragments of the present invention may be used to treat, e.g., primary and/or metastatic tumors arising in the brain and meninges, oropharynx, lung and bronchial tree, gastrointestinal tract, male and female reproductive tract, muscle, bone, skin and appendages, connective tissue, spleen, immune system, blood forming cells and bone marrow, liver and urinary tract, and special sensory organs such as the eye. In certain embodiments, the antibodies and antigen-binding fragments of the invention are used to treat one or more of the following cancers: renal cell carcinoma, pancreatic carcinoma, breast cancer, prostate cancer, malignant gliomas, osteosarcoma, colorectal cancer, malignant mesothelioma, multiple myeloma, ovarian cancer, small cell lung cancer, non-small cell lung cancer, synovial sarcoma, thyroid cancer, or melanoma. In certain embodiments, the antibodies and antigen-binding fragments of the invention are used to treat or prevent influenza infection or sepsis.

Combination Therapies

The present invention includes therapeutic administration regimens which comprise administering an anti-Tie2 antibody of the present invention in combination with at least one additional therapeutically active component. Non-limiting examples of such additional therapeutically active components include, for example, another Tie2 antagonist (e.g., an anti-Tie2 antibody), an antagonist of epidermal growth factor receptor (EGFR) (e.g., anti-EGFR antibody [e.g., cetuximab or panitumumab] or small molecule inhibitor of EGFR activity [e.g., gefitinib or erlotinib]), an antagonist of another EGFR family member such as Her2/ErbB2, ErbB3 or ErbB4 (e.g., anti-ErbB2, anti-ErbB3 or anti-ErbB4 antibody or small molecule inhibitor of ErbB2, ErbB3 or ErbB4 activity), an antagonist of EGFRvIII (e.g., an antibody that specifically binds EGFRvIII), a cMET anagonist (e.g., an anti-cMET antibody), an IGF1R antagonist (e.g., an anti-IGF1R antibody), a B-raf inhibitor (e.g., vemurafenib, sorafenib, GDC-0879, PLX-4720), a PDGFR-α inhibitor (e.g., an anti-PDGFR-α antibody), a PDGFR-β inhibitor (e.g., an anti-PDGFR-β antibody), a VEGF antagonist (e.g., a VEGF-Trap, see, e.g., U.S. Pat. No. 7,087,411 (also referred to herein as a “VEGF-inhibiting fusion protein”), anti-VEGF antibody (e.g., bevacizumab), a small molecule kinase inhibitor of VEGF receptor (e.g., sunitinib, sorafenib or pazopanib)), a DLL4 antagonist (e.g., an anti-DLL4 antibody disclosed in US 2009/0142354 such as REGN421), an Ang2 antagonist (e.g., an anti-Ang2 antibody disclosed in US 2011/0027286 such as H1H685P), etc. Other agents that may be beneficially administered in combination with the anti-Tie2 antibodies of the invention include cytokine inhibitors, including small-molecule cytokine inhibitors and antibodies that bind to cytokines such as IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-8, IL-9, IL-11, IL-12, IL-13, IL-17, IL-18, or to their respective receptors.

The present invention also includes therapeutic combinations comprising any of the anti-Tie2 antibodies mentioned herein and an inhibitor of one or more of VEGF, Ang2, DLL4, ErbB2, ErbB3, ErbB4, EGFRvIII, cMet, IGF1R, B-raf, PDGFR-α, PDGFR-β, or any of the aforementioned cytokines, wherein the inhibitor is an aptamer, an antisense molecule, a ribozyme, an siRNA, a peptibody, a nanobody or an antibody fragment (e.g., Fab fragment; F(ab′)₂ fragment; Fd fragment; Fv fragment; scFv; dAb fragment; or other engineered molecules, such as diabodies, triabodies, tetrabodies, minibodies and minimal recognition units). The anti-Tie2 antibodies of the invention may also be administered in combination with antivirals, antibiotics, analgesics, corticosteroids and/or NSAIDs. The anti-Tie2 antibodies of the invention may also be administered as part of a treatment regimen that also includes radiation treatment and/or conventional chemotherapy.

The additional therapeutically active component(s) may be administered just prior to, concurrent with, or shortly after the administration of an anti-Tie2 antibody of the present invention; (for purposes of the present disclosure, such administration regimens are considered the administration of an anti-Tie2 antibody “in combination with” an additional therapeutically active component). The present invention includes pharmaceutical compositions in which an anti-Tie2 antibody of the present invention is co-formulated with one or more of the additional therapeutically active component(s) as described elsewhere herein.

Diagnostic Uses of the Antibodies

The anti-Tie2 antibodies of the present invention may also be used to detect and/or measure Tie2 in a sample, e.g., for diagnostic purposes. For example, an anti-Tie2 antibody, or fragment thereof, may be used to diagnose a condition or disease characterized by aberrant expression (e.g., over-expression, under-expression, lack of expression, etc.) of Tie2. Exemplary diagnostic assays for Tie2 may comprise, e.g., contacting a sample, obtained from a patient, with an anti-Tie2 antibody of the invention, wherein the anti-Tie2 antibody is labeled with a detectable label or reporter molecule. Alternatively, an unlabeled anti-Tie2 antibody can be used in diagnostic applications in combination with a secondary antibody which is itself detectably labeled. The detectable label or reporter molecule can be a radioisotope, such as ³H, ¹⁴C, ³²P, ³⁵S, or ¹²⁵I; a fluorescent or chemiluminescent moiety such as fluorescein isothiocyanate, or rhodamine; or an enzyme such as alkaline phosphatase, beta-galactosidase, horseradish peroxidase, or luciferase. Specific exemplary assays that can be used to detect or measure Tie2 in a sample include enzyme-linked immunosorbent assay (ELISA), radioimmunoassay (RIA), and fluorescence-activated cell sorting (FACS).

Samples that can be used in Tie2 diagnostic assays according to the present invention include any tissue or fluid sample obtainable from a patient which contains detectable quantities of Tie2 protein, or fragments thereof, under normal or pathological conditions. Generally, levels of Tie2 in a particular sample obtained from a healthy patient (e.g., a patient not afflicted with a disease or condition associated with abnormal Tie2 levels or activity) will be measured to initially establish a baseline, or standard, level of Tie2. This baseline level of Tie2 can then be compared against the levels of Tie2 measured in samples obtained from individuals suspected of having a Tie2 related disease or condition.

EXAMPLES

The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use the methods and compositions of the invention, and are not intended to limit the scope of what the inventors regard as their invention. Efforts have been made to ensure accuracy with respect to numbers used (e.g., amounts, temperature, etc.) but some experimental errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, molecular weight is average molecular weight, temperature is in degrees Centigrade, and pressure is at or near atmospheric.

Control Constructs Used in the Following Examples

An exemplary control construct (anti-Tie2 antibody) was included in several experiments described below for comparative purposes. The antibody, referred to as Control I, is a chimeric anti-Tie2 antibody with mouse heavy and light chain variable domains having the amino acid sequences of the corresponding domains of “12H8”, as set forth in U.S. Pat. No. 6,376,653. The constant domain of this antibody is human IgG4.

Example 1. Generation of Human Antibodies to Human Tie2

Several human anti-Tie2 antibodies were generated by immunizing a VELOCIMMUNE® mouse with human Tie2 antigen according to standard methods (see, e.g., U.S. Pat. No. 6,596,541). Using this technique, several anti-Tie2 antibodies were obtained; exemplary antibodies generated in this manner, and their corresponding biological characteristics, are described in detail in the following Examples and include the antibodies designated H2aM2760N, H2aM2761N, H1M2055N, H1H2304B, H1H2317B, H1H2322B, H1H2324B, H1H2331B, H1H2332B, H1H2333S, H1H2337B, H1H2338B, H1H2339B, H1H2340B, and H4H2055N. The H1M, H2M, H1H, etc. prefixes on the antibody designations used herein indicate the particular Fc region of the antibody. For example, an “H2M” antibody has a mouse IgG2 Fc, whereas an “H4H” antibody has a human IgG4 Fc. As will be appreciated by a person of ordinary skill in the art, an Fc region of an antibody can be modified or replaced with a different Fc region, but the variable domains (including the CDRs) will remain the same.

Hybridomas which produce the anti-Tie2 antibodies H1M2055N, and H2aM2760N were deposited under terms in accordance with the Budapest Treaty with the American Type Culture Collection (ATCC), 10801 University Blvd., Manassas, Va. 20110-2209 on Dec. 2, 2011, under accession numbers PTA-12295 (H1M2055N) and PTA-12296 (H2aM2760N).

Example 2: Heavy and Light Chain Variable Region Amino Acid and Nucleic Acid Sequences

Table 1 sets forth the amino acid sequence identifiers of the heavy and light chain variable regions and CDRs of selected anti-Tie2 antibodies of the invention. The corresponding nucleic acid sequence identifiers are set forth in Table 2.

TABLE 1 Amino Acid Sequence Identifiers Antibody SEQ ID NOs: Designation HCVR HCDR1 HCDR2 HCDR3 LCVR LCDR1 LCDR2 LCDR3 H4H2332P 20 22 24 26 28 30 32 34 H4sH2339 36 38 40 42 44 46 48 50 H4sH2340 52 54 56 58 60 62 64 66

TABLE 2 Nucleic Acid Sequence Identifiers Antibody SEQ ID NOs: Designation HCVR HCDR1 HCDR2 HCDR3 LCVR LCDR1 LCDR2 LCDR3 H4H2332P 19 21 23 25 27 29 31 33 H4sH2339 35 37 39 41 43 45 47 49 H4sH2340 51 53 55 57 59 61 63 65

Example 3. Surface Plasmon Resonance Derived Binding Affinities and Kinetic Constants of Human Monoclonal Anti-Tie2 Antibodies

Binding affinities and kinetic constants of human monoclonal anti-Tie2 antibodies were determined by surface plasmon resonance at 25° C. and 37° C. (Tables 3-6). Measurements were conducted on a Biacore 2000 or T200 instrument.

For antibodies with a mouse constant region (designated H1M or H2M), antibodies were immobilized onto an anti-mouse Fc sensor surface and different concentrations of human, mouse or rat Tie2 constructs (hTie2-His, mTie2-hFc and rTie2-hFc) were injected over the antibody captured surface. For antibodies in the human IgG format (designated H1H or H4H), either an anti-human Fc sensor surface (hTie2-His and hTie2-mFc) or anti-human Fab sensor surface (mTie2-hFc and rTie2-hFc) was employed depending on the Tie-2 construct applied to the antibody captured surface. Amino acid sequences of the constructs used in this Example are as follows: hTie2-His (SEQ ID NO:2); hTie2-hFc (SEQ ID NO:3); hTie2-mFc (SEQ ID NO:4); rTie2-hFc (SEQ ID NO:5); and mTie2-hFc (SEQ ID NO:6).

Kinetic rate constants—association rate (ka) and dissociation rate (kd) were determined by fitting the real time binding sensorgrams to a 1:1 binding model with mass transport limitation using Scrubber 2.0 curve fitting software. The equilibrium dissociation constant (K_(D)) and dissociative half-life (T½) were calculated from the kinetic rate constants as: K_(D) (M)=kd/ka; and T % (min)=(ln 2/(60*kd). As shown in Tables 3-4, several antibodies demonstrated high affinity binding to hTie2 at both temperatures tested. In addition H1M2055N, H1H2332B, H1H2337B, H1H2340B and H4H2055N exhibited significant binding to mouse and rat Tie2 (Tables 5-6).

TABLE 3 Biacore binding affinities of human mAbs to hTie2 at 25° C. Binding at 25° Mab capture format T½ Antibody Analyte ka (Ms⁻¹) kd (s⁻¹) K_(D) (Molar) (min) H2aM2760N hTie2-His 2.91E+04 1.84E−04 6.32E−09 63 hTie2-hFc NT NT NT NT H2aM2761N hTie2-His 3.33E+04 1.01E−04 3.02E−09 115 hTie2-hFc NT NT NT NT H1M2055N hTie2-His 5.75E+05 1.34E−04 2.33E−10 86 hTie2-hFc NT NT NT NT H1H2304B hTie2-His 1.99E+05 1.32E−03 6.66E−09 9 hTie2-mFc 5.80E+05 3.75E−05 6.46E−11 308 H1H2317B hTie2-His 1.43E+05 9.26E−04 6.50E−09 12 hTie2-mFc 3.90E+05 2.36E−05 6.10E−11 489 H1H2322B hTie2-His 1.67E+05 9.76E−04 5.84E−09 12 hTie2-mFc 4.80E+05 1.39E−05 2.90E−11 829 H1H2324B hTie2-His 2.40E+05 9.25E−04 3.86E−09 12 hTie2-mFc 6.30E+05 5.92E−05 9.39E−11 195 H1H2331B hTie2-His 3.63E+04 1.17E−03 3.22E−08 10 hTie2-mFc 8.20E+04 1.24E−04 1.52E−09 93 H1H2332B hTie2-His 8.89E+04 2.23E−03 2.51E−08 5 hTie2-mFc 1.25E+05 2.13E−04  1.1E−09 54 H1H2333S hTie2-His 5.92E+04 3.09E−04 5.21E−09 37 hTie2-mFc NB NB NB NB H1H2337B hTie2-His 6.47E+04 6.49E−04 1.00E−08 18 hTie2-mFc 1.20E+05 1.11E−04 9.30E−10 104 H1H2338B hTie2-His 4.93E+04 3.44E−04 6.99E−09 34 hTie2-mFc NB NB NB NB H1H2339B hTie2-His 5.58E+04 1.25E−03 2.24E−08 9 hTie2-mFc 1.51E+05 1.02E−04 6.70E−10 114 H1H2340B hTie2-His 7.01E+04 3.45E−03 4.92E−08 3 hTie2-mFc 1.65E+05 1.91E−04 1.16E−09 60 H4H2055N hTie2-His 3.82E+05 4.84E−04 1.27E−09 24 hTie2-mFc 1.27E+06 9.92E−05 7.80E−11 116 Control I hTie2-His 6.53E+04 4.57E−04 7.00E−09 25 hTie2-mFc 1.45E+05 1.16E−04 8.03E−10 99 NB = no binding under the conditions tested NT = not tested

TABLE 4 Biacore binding affinities of human mAbs to hTie2 at 37° C. Binding at 37° Mab capture format T½ Antibody Analyte ka (Ms⁻¹) kd (s⁻¹) K_(D) (Molar) (min) H2aM2760N hTie2-His 4.04E+04 3.06E−04 7.60E−09 38 hTie2-hFc NT NT NT NT H2aM2761N hTie2-His 4.26E+04 2.87E−04 6.74E−09 40 hTie2-hFc NT NT NT NT H1M2055N hTie2-His 1.08E+06 3.36E−04 3.10E−10 34 hTie2-hFc NT NT NT NT H1H2304B hTie2-His 3.50E+05 3.67E−03 1.05E−08 3 hTie2-mFc 6.60E+05 1.30E−04 1.96E−10 89 H1H2317B hTie2-His 1.74E+05 3.46E−03 1.98E−08 3 hTie2-mFc 4.60E+05 9.94E−05 2.15E−10 116 H1H2322B hTie2-His 2.12E+05 4.74E−03 2.23E−08 2 hTie2-mFc 5.70E+05 9.72E−05 1.72E−10 119 H1H2324B hTie2-His 2.78E+05 2.26E−03 8.12E−09 5 hTie2-mFc 7.40E+05 1.47E−04 1.99E−10 79 H1H2331B hTie2-His 5.48E+04 4.74E−03 8.65E−08 2 hTie2-mFc 1.28E+05 1.99E−04 1.56E−09 58 H1H2332B hTie2-His 9.58E+04 8.19E−03 8.55E−08 1 hTie2-mFc 1.81E+05 6.52E−04 3.60E−09 18 H1H2333S hTie2-His 6.20E+04 9.83E−04 1.58E−08 12 hTie2-mFc NB NB NB NB H1H2337B hTie2-His 8.35E+04 2.41E−03 2.89E−08 5 hTie2-mFc 1.92E+05 2.55E−04 1.33E−09 45 H1H2338B hTie2-His 5.55E+04 9.93E−04 1.79E−08 12 hTie2-mFc NB NB NB NB H1H2339B hTie2-His 6.78E+04 4.88E−03 7.20E−08 2 hTie2-mFc 1.93E+05 2.95E−04 1.53E−09 39 H1H2340B hTie2-His 9.75E+04 9.98E−03 1.02E−07 1 hTie2-mFc 2.00E+05 5.15E−04 2.58E−09 22 H4H2055N hTie2-His 5.49E+05 8.01E−04 1.46E−09 14 hTie2-mFc 1.67E+06 1.55E−04 9.30E−11 74 Control I hTie2-His  7.48E−04 1.12E−03 1.49E−08 10 hTie2-mFc 1.80E+05 1.70E−04 9.40E−10 68 NB = no binding under the conditions tested NT = not tested

TABLE 5 Biacore binding affinities of human mAbs to mTie2 at 25° C. Binding at 25° Mab capture format T½ Antibody Analyte ka (Ms⁻¹) kd (s⁻¹) K_(D) (Molar) (min) H2aM2760N mTie2-hFc NB NB NB NB H2aM2761N mTie2-hFc NB NB NB NB H1M2055N mTie2-hFc 1.07E+06 1.85E−05 1.73E−11 625 H1H2304B mTie2-hFc NB NB NB NB H1H2317B mTie2-hFc NB NB NB NB H1H2322B mTie2-hFc NB NB NB NB H1H2324B mTie2-hFc NB NB NB NB H1H2331B mTie2-hFc 4.81E+04 2.72E−03 5.65E−08 4 H1H2332B mTie2-hFc 5.39E+04 5.76E−03 1.07E−07 2 H1H2333S mTie2-hFc NB NB NB NB H1H2337B mTie2-hFc 1.87E+05 1.84E−02 9.83E−08 1 H1H2338B mTie2-hFc NB NB NB NB H1H2339B mTie2-hFc 4.68E+04 2.63E−03 5.63E−08 4 H1H2340B mTie2-hFc 1.36E_05 6.72E−03 4.96E−08 2 H4H2055N mTie2-hFc 1.24E+06 6.19E−06 5.01E−12 1867 Control I mTie2-hFc NB NB NB NB NB = no binding under the conditions tested

TABLE 6 Biacore binding affinities of human mAbs to rTie2 at 25° C. Binding at 25° C. Mab capture format Antibody Analyte ka (Ms⁻¹) kd (s⁻¹) K_(D) (Molar) T1/2 H2aM2760N rTie2-hFc NB NB NB NB H2aM2761N rTie2-hFc NB NB NB NB H1M2055N rTie2-hFc 9.43E+05 2.55E−05 2.70E−11 454 H1H2304B rTie2-hFc NB NB NB NB H1H2317B rTie2-hFc NB NB NB NB H1H2322B rTie2-hFc NB NB NB NB H1H2324B rTie2-hFc NB NB NB NB H1H2331B rTie2-hFc NB NB NB NB H1H2332B rTie2-hFc 1.12E+05 6.18E−03 5.53E−08 2 H1H2333S rTie2-hFc NB NB NB NB H1H2337B rTie2-hFc 1.45E+05 8.46E−03 5.85E−08 1 H1H2338B rTie2-hFc NB NB NB NB H1H2339B rTie2-hFc NB NB NB NB H1H2340B rTie2-hFc 1.43E+05 3.71E−03 2.59E−08 3 H4H2055N rTie2-hFc 1.07E+06 1.00E−06 9.31E−13 11550 Control I rTie2-hFc NB NB NB NB NB = no binding under the conditions tested

Example 4. Epitope Mapping of Tie2 mAbs Using Luminex Beads

To determine domain binding for the anti-Tie2 antibodies, several hTie2 receptor extracellular domain-deletion constructs were covalently linked to luminex xMAP beads (10 μg/ml of each protein per 10⁷ beads). The constructs are depicted in FIG. 1 and are designated as follows: hTie2 (Ig1-Ig2-EGF) (SEQ ID NO:7); hTie2 (Ig2-EGF) (SEQ ID NO:8); hTie2 (EGF) (SEQ ID NO:9); hTie2 (Ig3-FN) (SEQ ID NO:10); and hTie2 (FN) (SEQ ID NO:11). Also tested in this Example were full-length hTie2-mFc (SEQ ID NO:4) and hTie1-hFc (SEQ ID NO:12) ectodomain constructs.

For binding, 25 μl of anti-Tie2 antibody (25 μg/ml) was added to 75 μl of the above created Luminex bead mixture (3×10³ beads per construct) in binding buffer (PBS, 0.05% Tween 20, 1 mg/ml BSA, 0.05% sodium azide) into a 96 well filter plate (Millipore). Incubation was at room temperature (RT) for 90 min or overnight at 4° C. with shaking. The beads were washed 3× with washing buffer (PBS+0.05% Tween 20) resuspended in 100 μl binding buffer containing PE (phycoerythrine)-labeled anti human kappa or PE-labeled anti mouse Fab secondary antibody and incubated at RT for 45 min with shaking. Samples were washed 2× more and binding signal (MFI) for each bead was determined using a Luminex L200 or FLEXMAP3D instrument. Bead linked human Tie2 was used as positive control and bead linked human Tie1 was used to measure family cross-reactivity. In general MFI signals greater than 500 units represent significant binding. Results are summarized in Table 7.

TABLE 7 Epitope mapping of Tie2 mAbs Predicted hTie2- hTie1- hTie2 hTie2 hTie2 hTie2 hTie2 Binding Antibody mFc hFc (EGF) (Ig1, Ig2, EGF) (Ig2, EGF) (FN)-hFc (Ig3, FN)-hFc Domain H2aM2760N 1668 15 4 9392 6245 341 330 Ig1, Ig2 H2aM2761N 8503 135 10205 11657 8568 3403 14509 EGF, Ig3 H1M2055N 753 112 90 2022 873 43 40 Ig1, Ig2 H1H2304B 4250 40 8901 8776 7648 5 6 EGF repeat H1H2317B 4853 37 9611 8966 8325 9 11 EGF repeat H1H2322B 4040 47 9901 9161 9167 10 13 EGF repeat H1H2324B 4506 31 9773 9438 8686 7 10 EGF repeat H1H2331B 5766 118 8 6 10 8097 6568 FN repeat H1H2332B 4783 32 3 3 4 6711 6044 FN repeat H1H2333S 1875 10 3 2 2 6 6 ND H1H2337B 5208 48 9 7 9 6425 7368 FN repeat H1H2338B 1385 9 4 5 5 6 8 ND H1H2339B 2913 62 6 5 6 4529 3838 FN repeat H1H2340B 3009 22 4 4 6 5149 4599 FN repeat Control I 4901 7 3 4 5 6105 4554 FN repeat ND = not determined

From the above results, it can be concluded that H2aM2760N and H1M2055N bind to the Ig1/Ig2 domains of Tie2; H2aM2761N binds to the EGF and Ig3 domains of Tie2; H1H2304B, H1H2317B, H1H2322B and H1H2324B bind to the EGF domain of Tie2; and H1H2331B, H1H2332B, H1H2337B, H1H2339B, H1H2340B, and Control I bind to the FN domain of Tie2.

Example 5. Epitope Mapping of H4H2055N Binding to Tie2 by H/D Exchange

Experiments were conducted to more precisely define the amino acid residues of Tie2 with which H4H2055N interacts. (H4H2055N is a fully human IgG4 version of the antibody H1M2055N produced from hybridoma PTA-12295.) For this purpose H/D exchange epitope mapping was carried out. A general description of the H/D exchange method is set forth in e.g., Ehring (1999) Analytical Biochemistry 267(2):252-259; and Engen and Smith (2001) Anal. Chem. 73:256A-265A.

To map the binding epitope(s) of antibody H4H2055N on Tie2 via H/D exchange, a recombinant construct consisting of the Ig1, Ig2 and EGF extracellular domains of human Tie2 (hTie2 (Ig1-Ig2-EGF); SEQ ID NO:7) was used. Antibody H4H2055N was covalently attached to N-hydroxysuccinimide (NHS) agarose beads (GE Lifescience).

In the ‘on-solution/off-beads’ experiment (on-exchange in solution followed by off-exchange on beads), the ligand (hTie2 Ig1-Ig2-EGF) was deuterated for 5 min or 10 min in PBS buffer prepared with D₂O, and then bound to H4H2055N beads through a 2 min incubation. The Tie2-bound beads were washed with PBS aqueous buffer (prepared with H₂O) and incubated for half of the on-exchange time in PBS buffer. After the off-exchange, the bound Tie2 was eluted from beads with an ice-cold low pH TFA solution. The eluted Tie2 was then digested with immobilized pepsin (Thermo Scientific) for 5 min. The resulting peptides were desalted using ZipTip® chromatographic pipette tips and immediately analyzed by UltrafleXtreme matrix assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry (MS).

In the ‘on-beads/off-beads’ experiment (on-exchange on beads followed by off-exchange on beads), Tie2 was first bound to H4H2055N beads and then incubated for 5 min or 10 min in D₂O for on-exchange. The following steps (off-exchange, pepsin digestion, and MS analysis) were carried out as described for the ‘on-solution/off-beads’ procedure. The centroid values or average mass-to-charge ratios (m/z) of all the detected peptides were calculated and compared between these two sets of experiments.

The results are summarized in Table 8 which provides a comparison of the centroid m/z values for all the detected peptides identified by liquid chromatography-matrix assisted laser desorption ionization (LC-MALDI) MS following the H/D exchange and peptic digest procedure. Likely due to disulfide bonds, the Tie2 sequence coverage detected from a single MALDI-TOF spectrum is relatively low. Nevertheless, more than half of the detected peptic peptides gave similar centroid values for both the on-solution/off-beads and on-beads/off-beads protocols. Three segments with corresponding residues 88-106, 139-152, and 166-175 had delta centroid values ≥0.20 m/z in both experiments. For purposes of the present Example a positive difference (Δ) of at least 0.20 m/z in both experiments indicates amino acids protected by antibody binding. Segments meeting this criterion are indicated by bold text and an asterisk (*) in Table 8.

TABLE 8 H4H2055N Binding to Tie2 Experiment I Experiment II 5 min on-/2.5 min 10 min on-/5 min off-exchange off-exchange Residues On- On- (of SEQ solution/ On-Beads/ solution/ On-Beads/ ID NO: 7) Off Beads Off-Beads Δ Off Beads Off-Beads Δ 20-33 1568.70 1568.63 0.07 1568.63 1568.63 0.00 26-33 1036.17 1036.16 0.01 1036.27 1036.21 0.07 38-50 1572.91 1572.93 −0.02 1572.78 1572.98 −0.20 39-50 1425.38 1425.39 0.00 1425.54 1425.45 0.08 42-53 1440.52 1440.44 0.09 1440.62 1440.52 0.10 42-58 2041.43 2041.42 0.01 2041.58 2041.41 0.17 78-87 1124.17 1124.15 0.03 1124.20 1124.14 0.07 88-95 1049.49 1049.46 0.02 1049.46 1049.54 −0.08  88-101* 1767.78 1767.51 0.27 1767.79 1767.57 0.22  88-102* 1881.08 1880.66 0.42 1881.14 1880.69 0.45  93-101* 1127.80 1127.57 0.24 1127.80 1127.61 0.19  93-102* 1241.46 1240.83 0.63 1241.34 1240.83 0.51  96-102* 850.54 850.22 0.32 850.55 850.25 0.30  96-106* 1233.29 1232.66 0.64 1233.43 1232.65 0.78  139-151* 1514.22 1513.16 1.06 1514.49 1513.21 1.28  139-152* 1643.17 1642.02 1.16 1643.44 1642.06 1.38 152-165 1498.87 1498.73 0.14 1498.88 1498.77 0.11 152-166 1662.09 1662.01 0.07 1662.10 1662.08 0.02 153-165 1369.70 1369.64 0.06 1369.77 1369.66 0.11  166-175* 1115.07 1114.59 0.47 1115.04 1114.65 0.39  167-175* 951.73 951.30 0.42 951.74 951.33 0.41

Since the peptide fragment (m/z of 1049.4) corresponding to residues 88-95 did not show deuteron retention (Δ=0) after off-exchange, the first protected segment (88-106) can be reduced to only include residues 96-106. Thus the three regions 96-106, 139-152, and 166-175 of SEQ ID NO:7 are protected from full off-exchange by H4H2055N binding to Tie2 after on-exchange.

The Ig1 domain of Tie2 consists of amino acids 1-97 of SEQ ID NO:7; the Ig2 domain of Tie 2 consists of amino acids 98-186 of SEQ ID NO:7; and the EGF repeat domain consists of amino acids 187-321 of SEQ ID NO:7. Thus the first binding region (amino acids 96-106 of SEQ ID NO:7) includes the last two amino acids of the Ig1 domain and the first 9 amino acids of the Ig2 domain. The second and third binding regions (amino acids 139-152 and 166-175 of SEQ ID NO:7) are located entirely within the Ig2 domain.

It should also be noted that the second and third binding regions (amino acids 139-152 and 166-175 of SEQ ID NO:7) lie within the amino acid region of Tie 2 that directly contacts its cognate ligand, Angiopoietin-2, based on the co-crystal structure by Barton et al. (2006, Nat Struct Mol Biol 13(6) 524-532). Therefore, this example suggests that antibody H4H2055N binds a discontinuous epitope primarily within the Ig2 domain of human Tie2 (with one or two potential amino acid contacts within the C-terminal portion of the Ig1 domain), and that binding to these regions correlates with the ability of H4H2055N to block the interaction between Tie2 and Ang2 as illustrated in Examples 6 and 7 herein.

Example 6. Assessment of the Ability of Anti-Tie2 Antibodies to Block the Interaction Between Tie2 and Angiopoietins

Tie2 is known to interact with angiopoietins (Ang1, Ang2, Ang3 and Ang4). An initial set of experiments was therefore conducted to evaluate the ability of anti-Tie2 antibodies to block Tie2 binding to Ang2. In this first set of experiments, a quantitative blocking immunoassay was utilized. Briefly, solutions of 0.8 nM biotinylated ecto-Tie2 fused to 6× His (SEQ ID NO:2) were premixed with anti-Tie2 antibody ranging from 50 nM to 0 nM in serial dilutions. After a 1-hour incubation at room temperature, the amount of Tie2-His bound to plate coated Bow-Ang2 was measured by sandwich ELISA. Bow-Ang2 (SEQ ID NO:13), an Ang2 construct that comprises the Fc domain of hIgG1 flanked by one FD domain of Ang2 at both termini, was coated at 2 μg/ml on a 96 well microtiter plate and blocked with BSA. Plate-bound biotin-Tie2-His was detected using HRP conjugated streptavidin, and developed using BD OptEIA™ (BD Biosciences Pharmingen, San Diego, Calif.). Signals of OD₄₅₀ nm were recorded and data was analyzed using GraphPad Prism to calculate IC₅₀ values. Results are summarized in Table 9. IC₅₀s were defined as the amount of antibody required to reduce 50% of biotin-Tie2-His detectable to plate bound Bow-Ang2 ligand. In Table 9, an antibody is designated an “enhancer” if the addition of the antibody increases the amount of Tie2-His bound to the Bow-Ang2-coated surface relative to the no antibody control.

TABLE 9 IC₅₀ values for anti-Tie2 Mabs blocking of hTie2 to plate bound Bow-Ang2 Result in Blocking of binding Blocking to Bow-Ang2 Antibody ELISA IC₅₀ (M) H2aM2760N Enhancer N/A H2aM2761N Enhancer N/A H1M2055N Enhancer N/A H1H2304B Enhancer N/A H1H2317B Enhancer N/A H1H2322B Enhancer N/A H1H2324B Enhancer N/A H1H2331B Enhancer N/A H1H2332B Enhancer N/A H1H2333S Enhancer N/A H1H2337B Enhancer N/A H1H2338B Enhancer N/A H1H2339B Blocker 1.89E−10 H1H2340B Blocker 1.03E−09 H4H2055N Blocker 1.06E−09 Control I Enhancer N/A

This first set of experiments demonstrates that anti-Tie2 antibodies H1H2339B, H1H2340B and H4H2055N are able to block the interaction between Ang2 and Tie2 in an ELISA format.

A further set of experiments was conducted to evaluate the ability of H4H2055N to block Tie2 binding to Ang2 and other members of the angiopoietin family (Ang1, Ang3 and Ang4). In this set of experiments, an Octet Red biosensor was employed using two experimental formats. In the first format, hTie2.mFc (SEQ ID NO:4; 10 μg/ml) or a negative control was captured on anti-mFc Octet senor tips for 5 min. The captured sensor tip surfaces were then saturated with H4H2055N or Control I antibody by dipping into wells containing 300 nM of respective monoclonal antibodies for 10 min. Finally the sensor tips were placed into wells containing 100 nM of hAng1 (R&D Systems, Inc., Minneapolis, Minn., Cat 923-AN/CF; Accession #Q5HYAO), hAng2 (R&D Systems, Inc., Minneapolis, Minn., Cat 623-AN/CF; Accession #015123), mAng3 (R&D Systems, Inc., Minneapolis, Minn., Cat 738-AN/CF; Accession #Q9WVH6) or hAng4 (R&D Systems, Inc., Minneapolis, Minn., Cat 964-AN/CF; Accession Q9Y264) for 5 min. Binding response at each step of the experiment was monitored and the binding of different angiopoietins to the monoclonal antibody saturated receptor surfaces was plotted (FIG. 2). As illustrated by FIG. 2, H4H2055N blocked the binding of all four angiopoietins to the hTie2.mFc surface. The Control I antibody did not block binding of any of the angiopoietins to the Tie2-coated surfaces.

In the second assay format, hTie2.mFc (10 μg/ml) or negative control was captured on anti-mFc coated Octet sensor tips (5 min), followed by placing the tips into different wells containing 100 nM of angiopoietin (hAng1, hAng2, mAng3 or hAng4) for 10 min. Lastly, the senor tips were placed into wells containing 300 nM of H4H2055N or Control I (5 min). As in format 1, the binding response at each step was monitored and the binding response was plotted (FIG. 3). This format demonstrated that, unlike Control I, the binding of H4H2055N is diminished by the already bound angiopoietins on the Tie2-coated surfaces. Thus, H4H2055N competes with the angiopoietins (Ang1, Ang2, Ang3 and Ang4) for binding to Tie2.

Example 7. Assessment of the Ability of Anti-Tie2 Antibodies to Block Angiopoietin-Mediated Tie2 Signaling

To further characterize anti-hTie2 mAbs of the invention, the ability of the antibodies to block Tie2-induced luciferase activity was explored. Briefly, HEK293 cells were stably transfected with hTie2, and the top 10% of Tie2 expressing cells were isolated via FACS. These cells were then transduced with a serum response element (SRE)-dependent luciferase reporter lentivirus (SA Biosciences), and a clonal population (293-TIE2/SRE-Luc) with robust response to tetrameric forms of angiopoietin-1 (Bow-Ang1, SEQ ID NO:14) and angiopoietin-2 (Bow-Ang2, SEQ ID NO:13) was isolated.

For assays, 293-Tie2/SRE-Luc cells were seeded (30,000 cells per well) in 96-well plates one day prior to treatment. Dose-response curves were generated with serial dilutions of Bow-Ang1 (BA1) or Bow-Ang2 (BA2) incubated with cells for 4 h before measurement of luciferase activity. For Tie2 inhibition, cells were treated with serially diluted Tie2 mAbs in the presence of a 1 nM constant dose of BA1 or BA2 for 4 h. Luciferase activity was measured on a Victor luminometer following incubation with One-Glo™ (Promega) reagent. Three classes of antibodies were observed: Blockers, defined as a reduction in Tie2 dependent luciferase activity upon addition of antibody; Activators, defined as an increase in Tie2 dependent luciferase activity upon addition of antibody; and Not Active, defined as no significant change in signal upon their addition. For “Not Active” antibodies, no EC₅₀ or IC₅₀ value was calculated. Results are summarized in Table 10.

TABLE 10 IC₅₀ values for Anti-Tie2 antibodies EC₅₀ or EC₅₀ or IC₅₀ ± SEM IC₅₀ ± SEM Mab Class (10⁻⁹M) Mab Class (10⁻⁹M) Antibody (BowAng1) BowAng1 (BowAng2) BowAng2 H2aM2760N Blocker 11.6 ± .81 Blocker 2.8 ± .14 H2aM2761N Blocker, not  5.2 ± 1.3 Blocker, not to 1.1 ± .11 to baseline baseline H4H2055N Blocker 0.69 ± .16 Blocker 0.23 ± .03  H1H2304B No activity NA No activity NA H1H2317B No activity NA No activity NA H1H2322B No activity NA No activity NA H1H2324B No activity NA No activity NA H1H2331B Activator 13.6 ± 3.1 Activator 5.1 ± 1.9 H1H2332B Activator  2.5 ± 1.2 Activator 3.7 ± .15 H1H2333B No activity NA No activity NA H1H2337B Activator  1.1 ± .02 Activator 4.7 ± .80 H1H2338B No activity NA No activity NA H1H2339B Activator 10.3 ± .23 Activator 13.0 ± 3.5  HIH2340B Activator 1.41 ± .01 Activator 2.1 ± .04 Control I Activator 0.76 ± .50 Activator 1.4 ± .03 IC₅₀ values are reported for Blockers, and EC₅₀ values are reported for Activators

Anti-Tie2 antibodies H2aM2760N, H2aM2761N and H4H2055N were identified as blockers in this experimental system. Anti-Tie2 antibodies H1H2332B, H1H2339B and H1H2340B were identified as activators of both BowAng1 and BowAng2.

Example 8. Assessment of the Anti-Tumor Activity of an Anti-Tie2 Antibody In Vivo

An exemplary anti-Tie2 antibody (H2M2055N) was tested for its ability to inhibit the growth of human tumor xenografts in immunocompromised mice. Briefly, either human colorectal HT29 or Colo205 tumors were grown in SCID mice. When tumors were palpable (100 mm³ for HT29 and 400 mm³ for Colo205) animals were treated biweekly with Fc protein (10 mg/kg) or anti-Tie2 antibody (H1M2055N; 10 mg/kg). At the end of treatment (31 days for HT29 & 14 days for Colo205), the percent tumor growth inhibition (% TGI) was determined (Table 9) and tumor tissue was harvested and utilized for vessel density analysis. Vascular density was assessed in 30 μm thick OCT tumor sections by CD31 immunohistochemistry. NIH Image software was utilized to determine the % area vessel density in the tumor tissue sections. Results are illustrated graphically in FIGS. 4-7.

TABLE 11 Percent Decrease in Tumor Growth with Anti-Tie2 Mab Treatment HT29 Colo205 Avg Tumor Avg Tumor % Growth (mm3) % Decrease Growth (mm3) Decrease from start of in Tumor from start of in Tumor Antibody treatment Growth treatment Growth Fc protein 100 400 (10 mg/kg) H2M2055N 100 27.5 400 77 (10 mg/kg)

As shown in this Example, the anti-Tie2 Ab, H1M2055N, not only decreased tumor growth (Table 9), but also significantly decreased vessel density in both HT29 (25%, FIG. 5) and Colo205 (40%, FIG. 7) xenograft models.

Example 9: Tie2 Activating mAbs for Vascular Leak

HUVEC cells were seeded on collagen-coated 24-well transwell inserts (1 μm filter) and grown for 48 h to confluence. Transepithelial electrical resistance (TEER) was measured on a daily basis to confirm monolayer formation (EVOM-2, World Precision Instruments). Cells were treated for 24 h with TNF-α in the presence or absence of combinations of Tie2 activating antibodies (either H4H2340P/H4H2339P or H4H2332P/H4H2339P). Permeability was determined by measurement of the fluorometric signal (485/535 nm) in the abluminal chamber 1 hour after addition of 0.5 mg/mL (75 μg/insert) FITC-Dextran (70 kD) to the luminal chamber, using the Spectramax i3× Detection Platform (Molecular Devices). Percent permeability relative to the untreated control was calculated using the following equation: % permeability=(Fluorescence_(sample)−Fluorescence_(Min Signal Ctrl (Untreated)))/(Fluorescence_(Max Signal Ctrl (No cells))−Fluorescence_(Min Signal Ctrl (Untreated)))).

As shown in FIG. 8 and Table 12, below, on confluent HUVECs, the addition of TNF-α leads to an increase in permeability compared to untreated HUVECs, suggesting a disruption of cell to cell contact. Addition of 166.7 nM of either combination of Tie2 activating antibodies (H4H2340P/H4H2339P or H4H2332P/H4H2339P) reduced the passage of FITC-Dextran through the disrupted HUVEC monolayer by 30.7% and 53.8%, respectively compared to TNF alone suggesting a decrease in the formation of intercellular gaps in the endothelial barrier.

TABLE 12 Average percent permeability relative to the untreated cell control. TNF-α + REGN1945 (hIgG4 Ctrl) Untreated TNF-α + TNF-α + H4H2340P/ Isotype No cells cells TNF-α H4H2332P/H4H2339P H4H2339P Control 100.00 ± 7.14 0.00 ± 0.15 10.81 ± 0.88 5.00 ± 0.45 7.50 ± 0.38 9.60 ± 0.63

Example 10: Tie2 Activating mAbs for Vascular Leak in an In Vivo Mouse Model of Influenza and Sepsis

Seven-week old, female BALB/c mice were anesthetized with a ketamine/xylazine mixture before receiving an intranasal infection with 10× mouse LD₅₀ (450 PFUs/mouse) of A/Puerto Rico/08/1934 (H1N1) in 20 μL saline. AT 2- and 4-days post-infection (p.i.) the mice were treated with a subcutaneous dose of 20 mg/kg of each Tie2 mAb combinations (40 mg/kg total of H4H2340P/H4H2339P or H4H2332P/H4H2339P) and/or isotype control. On day 3 p.i., mice received an intravenous dose of 12 mg/kg of the anti-influenza A group 1 mAb H1H11729P, an anti-influenza HA or isotype control (see, e.g., US 2016/0176953, incorporated by reference). All mice were monitored daily for 14 days. Death was determined by a 25% body weight loss threshold that was authorized by the Regeneron Institutional Animal Care and Use Committee. Results are reported in Table 13 as percent survival.

TABLE 13 Therapeutic administration of activating Tie2 mAbs in combination with anti-influenza A hemagglutinin mAb Number surviving/total Group Treatment N (percent) 1 Uninfected saline control  5/5 (100) 2 H1H11729P + H4H2340P/H4H2339P 4/5 (80) 3 H1H11729P + H4H2332P/H4H2339P 3/5 (60) 4 H1H11729P + IgG4 isotype control 2/5 (40) 5 H4H2340P/H4H2339P + IgG1 isotype control 1/5 (20) 6 H4H2332P/H4H2339P + IgG1 isotype control 1/5 (20) 7 IgG1 isotype control + IgG4 isotype control 0/5 (0) 

As shown in Table 13, the Tie2 mAbs H4H2340P/H4H2339P or H4H2332P/H4H2339P showed robust efficacy in combination with the anti-influenza A group 1 hemaglutinning mAb, H1H17729P in treating mice infected with a historical influenza strain as shown in Table 14 and FIG. 9. The combination of a single dose of H1H11729P with two doses of H4H2340P/H4H2339P resulted in 80% survival compared to either treatments given alone with isotype control mAbs (40% and 20%, respectively; Table 13 and FIGS. 9 and 10). The combination of a single dose of H1H11729P with two doses of H4H2332P/H4H2339P resulted in 60% survival compared to 40% and 20% survival with either treatment alone. Mice dosed with isotype control mAbs only all died by day 7 post-infection. These results show that therapeutic administration of activating Tie2 mAbs in combination with an anti-pathogen-specific mAb improves survival compared to treatment with the anti-hemagglutinin-specific mAb alone after lethal challenge with Influenza A.

Ten-week old, male C57/BL6 mice were treated with a subcutaneous dose of 20 mg/kg of each Tie2 mAb combination (40 mg/kg total of H4H2340P/H4H2339P or H4H2332P/H4H2339P) or isotype control 48 h before intoxication. On the day of intoxication (time 0), LPS was reconstituted to a dose of 25 mg/kg mouse by sonication and LPS was administered intraperitonally. All mice were monitored daily for 7 days every 6 hours. Death was determined by a 20% body weight loss threshold. Results are reported as percent survival.

The Tie2 mAbs H4H2340/H4H2339P showed efficacy when given prophylactically in an LPS sepsis model (Table 14 and FIG. 10). Mice that received 40 mg/kg of the H4H2332P/H4H2339P combination, isotype control or PGS only were all dead by 24 or 48 hours post-intoxication. Mice that received 40 mg/kg total of the H4H2340P/H4H2339P combination 48 h before intoxication showed delayed death and 20% survival. These results show that prophylactic administration of a combination of activating Tie2 mAbs improves survival and delays death in a very lethal model of sepsis.

TABLE 14 Prophylactic administration of activating Tie2 mAbs H4H2340P/H4H2339P delays death and improves survival in a lethal model of E. coli 0111:B4 LPS intoxication over isotype/untreated controls. Number surviving/total Group Treatment N (percent) 1 Unintoxicated saline control  5/5 (100) 2 H4H2340P/H4H2339P  1/5 (20) 3 H4H2332P/H4H2339P 0/5 (0) 4 IgG4 isotype control 0/5 (0) 5 Saline alone 0/5 (0)

As shown in FIG. 10, prophylactic administration of activating Tie2 mAbs, H4H2340P/H4H2339P resulted in a delay in death and increase in survival after intoxication. Mice received a single dose of H4H2340P/H4H2339 or H4H2332P/H4H2339P (40 mg/kg total on 2 days before intoxication, SC). LPS was administered IP at time 0. Results from one experiment (N=5) are shown.

The present invention is not to be limited in scope by the specific embodiments describe herein. Indeed, various modifications of the invention in addition to those described herein will become apparent to those skilled in the art from the foregoing description and the accompanying figures. Such modifications are intended to fall within the scope of the appended claims. 

1. An isolated antibody or antigen-binding fragment thereof that binds human Tie2 receptor, wherein the antibody or antigen-binding fragment thereof comprises: (a) the complementarity determining regions (CDRs) of a heavy chain variable region (HCVR) comprising the amino acid sequence of SEQ ID NO: 20, SEQ ID NO: 36, or SEQ ID NO: 52 and (b) the CDRs of a light chain variable region (LCVR) comprising the amino acid sequence of SEQ ID NO: 28, SEQ ID NO: 44, or SEQ ID NO:
 60. 2. The isolated antibody or antigen-binding fragment of claim 1, wherein the antibody or antigen-binding fragment comprises the heavy and light chain CDRs of an HCVR/LCVR amino acid sequence pair selected from the group consisting of SEQ ID NOs: 20/28, 36/44, and 52/60.
 3. The isolated antibody or antigen-binding fragment thereof of claim 2, wherein the antibody or antigen-binding fragment thereof comprises an HCVR/LCVR amino acid sequence pair selected from the group consisting of SEQ ID NOs: 20/28, 36/44, and 52/60.
 4. The isolated antibody or antigen-binding fragment thereof of claim 2, wherein the antibody or antigen-binding fragment thereof activates Tie2 signaling.
 5. The antibody or antigen-binding fragment of claim 1, wherein the antibody or antigen-binding fragment thereof competes for binding to Tie2 with a reference antibody comprising an HCVR/LCVR amino acid sequence pair selected from the group consisting of SEQ ID NOs: 20/28, 36/44, and 52/60.
 6. The antibody or antigen-binding fragment thereof of claim 1, wherein the antibody or antigen-binding fragment thereof binds to the same epitope on Tie2 as a reference antibody comprising an HCVR/LCVR amino acid sequence pair selected from the group consisting of SEQ ID NOs: 20/28, 36/44, and 52/60.
 7. A pharmaceutical composition comprising the antibody or antigen-binding fragment thereof of claim 1, and a pharmaceutically acceptable carrier or diluent.
 8. A pharmaceutical composition comprising the antibody or antigen-binding fragment thereof of claim 2, and a pharmaceutically acceptable carrier or diluent.
 9. A pharmaceutical composition comprising the antibody or antigen-binding fragment thereof of claim 3, and a pharmaceutically acceptable carrier or diluent. 10-20. (canceled)
 21. The isolated antibody or antigen-binding fragment thereof of claim 1, wherein the antibody or antigen-binding fragment thereof comprises an HCVR amino acid sequence selected from the group consisting of SEQ ID NOs: 20, 36, and
 52. 22. The isolated antibody or antigen-binding fragment thereof of claim 1, wherein the antibody or antigen-binding fragment thereof comprises an LCVR amino acid sequence selected from the group consisting of SEQ ID NOs: 28, 44, and
 60. 23. The isolated antibody or antigen-binding fragment of claim 2, wherein the antibody or antigen-binding fragment thereof comprises: (a) an HCDR1 comprising the amino acid sequence of SEQ ID NO: 22; (b) an HCDR2 comprising the amino acid sequence of SEQ ID NO: 24; (c) an HCDR3 comprising the amino acid sequence of SEQ ID NO: 26; (d) an LCDR1 comprising the amino acid sequence of SEQ ID NO: 30; (e) an LCDR2 comprising the amino acid sequence of SEQ ID NO: 32; and (f) an LCDR3 comprising the amino acid sequence of SEQ ID NO:
 34. 24. The isolated antibody or antigen-binding fragment of claim 2, wherein the antibody or antigen-binding fragment thereof comprises: (a) an HCDR1 comprising the amino acid sequence of SEQ ID NO: 38; (b) an HCDR2 comprising the amino acid sequence of SEQ ID NO: 40; (c) an HCDR3 comprising the amino acid sequence of SEQ ID NO: 42; (d) an LCDR1 comprising the amino acid sequence of SEQ ID NO: 46; (e) an LCDR2 comprising the amino acid sequence of SEQ ID NO: 48; and (f) an LCDR3 comprising the amino acid sequence of SEQ ID NO:
 50. 25. The isolated antibody or antigen-binding fragment of claim 2, wherein the antibody or antigen-binding fragment thereof comprises: (a) an HCDR1 comprising the amino acid sequence of SEQ ID NO: 54; (b) an HCDR2 comprising the amino acid sequence of SEQ ID NO: 56; (c) an HCDR3 comprising the amino acid sequence of SEQ ID NO: 58; (d) an LCDR1 comprising the amino acid sequence of SEQ ID NO: 62; (e) an LCDR2 comprising the amino acid sequence of SEQ ID NO: 64; and (f) an LCDR3 comprising the amino acid sequence of SEQ ID NO:
 66. 26. A pharmaceutical composition comprising the antibody or antigen-binding fragment thereof of claim 23, and a pharmaceutically acceptable carrier or diluent.
 27. A pharmaceutical composition comprising the antibody or antigen-binding fragment thereof of claim 24, and a pharmaceutically acceptable carrier or diluent.
 28. A pharmaceutical composition comprising the antibody or antigen-binding fragment thereof of claim 25, and a pharmaceutically acceptable carrier or diluent.
 29. The isolated antibody or antigen-binding fragment of claim 3, which is an antibody.
 30. The isolated antibody of claim 29, wherein the isolated antibody comprises an IgG4 heavy chain constant region.
 31. The isolated antibody of claim 29, wherein the isolated antibody comprises an IgG1 heavy chain constant region. 